I made one of these when I hit immortal for the first time and I generally agree with most of what I wrote, but I have changed my mind on some things. I thought I'd write another one now that I've stepped it up.
First I'll give some generalized tips about ranked in general and then I'll give some advice for different ranks after that. (You should 100% read the generalized first) Some of this is repeated information from my older tips, I tried to focus on increasing the generalized tips and the section for making the jump from Immortal to Radiant.

General:
- Pick one agent and get great at them, you should not be filling every single game. There is an exception for this at the very bottom and top ranks I would say, but if you're seriously trying to get good at the game you need to at minimum be playing one role. Imagine you're on a baseball team and trying to be a great pitcher and hitter at the same time; it just doesn't really work unless you're just that guy.
- It is your fault. There are games where you can definitely blame your team and you sometimes just roll an instant loss, but it's certainly possible to 1v9 all the way until high immortal/radiant. Certain pros are able to do it there, too.
- You need a microphone. You are seriously handicapping yourself and your teammates by not being able to communicate. You will think your teammates are stupid for not thinking what you're thinking, but to them, you're equally stupid because you didn't ask them what they wanted to do, or make a plan for them to follow. Don't expect people to read your minds. Also, comming and keeping a good vibe with your teammates will definitely keep the team morale/mental up.
- If you're someone who prones to tilting, (Trust me I am in this category) you need to take breaks in between games. I've had sessions where I get frustrated off of one loss and then proceed to lose 100 RR because I wanted to roll a good team, but in the process started playing worse because I was more focused on my teammates failures than my own successes. Also, if you're going to get frustrated, don't let it show to your teammates. You're going to make them play worse 95% of the time. Nobody wants to be yelled at for doing their thing. Not only this, if you're going to get mad, you should be annoyed at the close games where you could've had more of an impact, not the games where you're losing by 9 and have no chance of winning regardless, and just need to enter the next match with a good mental state.
- Instalock. This doesn't mean instalock duelist, but you should just be picking what you're good at. Team composition does NOT matter, I regularly win with 3-4 duelists all the time. The way I go about team comps is as long as you have smokes and some type of dog/drone the rest doesn't matter. No you do not need to be yelling at your Jett player for not picking Raze on split in your diamond game. I promise you it does not matter even in the slightest.
- Focus on learning something from each match. Also, unless you're in iron or bronze where team coordination and aim are non-existent, you should try to use smurfs and bad teammates to work on coordinated plays like swinging together and having setups, rather than expecting your "bad" teammates to out-aim smurfs. Never easy to kill someone while you're blinded by a skye flash or have three people swinging you at the same time.
- Pay attention, the worst thing you can do in ranked is autopilot. This is the only way you won't improve. If it's two in the morning and you're really tired and don't think you could easily do some math homework, you shouldn't be playing Valorant either. Everyone is trying their hardest to outsmart you in that match and being tired or unfocused is only going to hurt you.
- Work. Practice makes perfect and you can't watch some random YouTube video and expect to rank up and be a much better player instantly after watching it. There's no "trick" to getting better. You are still gonna have to aim train, and you're still gonna have to grind ranked to learn the game.
- Play to win EVERY. SINGLE. ROUND. I don't care if you're up 8 rounds and it's 5v1. If you are seriously wanting to win, you better be playing like it's a VCT tournament. Always be patient waiting for drone, don't just "run in" and don't just push the last guy with terrible odds of actually winning that fight. That's how you lose free rounds.
- Healer is NOT a role. It's just not. You don't need healing literally ever. It's convenient and nice to have, but you literally just don't need it.
- If you have a fight that's better than a 50% chance of winning, take it. (Unless you're up 2 or more people)
- Only take 50/50 fights if you're down numbers.
- Literally just play your objectives. You don't have to kill all five players every single round to win it.
- Unless the round is close enough to where your comms can make enough of an impact can win the round, just analyze what you could've done better in previous rounds or what you can do in the next rounds to win the game.
- There's a difference between calling strats for your team and backseating. "Hey guys let's go B, wait for drone, flash out and we win" and micromanaging people are completely different. Also, aside from certain things the player might not notice like time or ammo, or if they clearly did not hear some footsteps or something, SHUT UP DURING SOMEONE'S CLUTCH
- Learn to dodge. Not worth losing 20 rr when you could've just lost 3 and won your next game.
- Finally, setup and settings aren't crazy important but there are a few things you need to do to make the game playable. A consistent 60fps and sub-70 ping are needed to be playable in my opinion. You also need a decent mouse that doesn't bug out when you swipe it too fast. Also, sensitivity is something people worry about all the time, and while it IS personal preference and there are certain pros that are good enough with wildly high sensitivities, they're rare exceptions for a reason, and you're making it hard on yourself for no purpose. Something between 160-400 eDPI (DPI*Sensitivity) is necessary to make the game playable without having to be particularly cracked to make it to the top ranks. You don't need TenZ level aim to make it to the high ranks, but there's no reason to make it harder than it needs to be!

One other tiny thing is that I'll leave a few good sources at the end for educational and practice purposes.

Iron-Silver:

- As long as you have headphones and are trying to stay alive with common sense, all you need to work on in the lower ranks is your mechanics. Start aim training, nothing ridiculous, but 15 minutes a day seems reasonable for most people who have the time to play video games, and look up different guides for crosshair placement, and how to properly peek.
- Regarding aiming, you don't need to have your mouse flying across the table insanely fast to look cool, but you shouldn't be taking two entire seconds to line up a shot, shooting and missing a few times will lead to improvement, taking forever only works against other irons. Also, don't shoot the millisecond you see someone. Adjust your mouse and then fire. Crosshair placement exists to make your shots easier, not to just click when you see someone.
- Pick Reyna and just frag out in these ranks, not only does utility not really matter but you're not going to have the understanding of it to use it correctly in the first place. I also think Phoenix is a sleeper pick in all ranks to learn the game because he has a bit of each type of utility, not to mention his flash is insanely busted and basically un-reactable so if you use it right you're gonna get tons of free kills.
- In tandem with good mechanics, movement is insanely important as well. There are a million guides on YouTube and some stuff I will mention at the end that can help you a ton with this stuff

Gold:

- This is really where the game "starts" in my opinion. People finally understand the game enough to where you can't just run it down and out-aim people (unless you're THAT much better than them). Start evaluating the risks you take. If you have less than a 60% chance of succeeding when you peek an angle, don't peek it.
- Your awareness is terrible and you're not rotating at the right times. Look at your map every 5-10 seconds, and keep in mind that just because they're "Hitting A" doesn't mean there can't be stragglers in other parts of the map.
- You're not "lurking", you're playing bad so you decide to go to the other site and don't find any kills and don't do anything while your team is dying.
- Additionally, lurking is generally around the middle of the map, flanking the other team in the MIDDLE of retaking, and catching off people that are rotating. (It's extremely easy in gold, but gets much harder the higher rank you go.)
- You're not entrying and you're waiting for your teammates to die for no reason. (You're GOING to get teammates that bait you. This is why playing Jett is so effective in solo queue. She doesn't need help until very high ranks and your teammates will bait you in any rank so being the person built to entry is very helpful.
- You're investing your ult in terrible rounds. If you have a really low chance of winning a round, don't use it. (There are exceptions, duh. Reyna and Jett for example have ults that can completely turn a low-chance round around.)
- "Default" does not mean you just sit in spawn and do nothing. You go up slow and make mid-round decisions with your team based on the information you get. Also, stick with a teammate so you don't just get picked off alone.
- You don't watch angles that your teammates can't hold
- Stop relying on Killjoy and Cypher to give you map awareness. You should be focusing on knowing where people can be off of intuition, and you should be clearing angles without having a drone do it for you.

Platinum:

- You are getting rolled by an awp because you don't know how to play around it. Smoking an awp out generally makes it useless, initiator utility is incredibly important for clearing out shotguns and awps. If you're dying to an awp, it better be because they found a crafty way to dodge your utility or catch you off guard in an off-angle, not just because you swung an angle at the start of a round and an awper was holding it.
- Learn when to play retake, if the enemy is just spamming util on site and then playing post plant on site, staying alive and hopefully getting a cheap kill or some damage off and then waiting for your team is pretty effective.
- If you do your job, and hopefully get a few plays during the game with good utility, you don't need to constantly try to carry. People in plat will know how to punish your stupid aggression and kill-hungry plays.
- A smoke is not a wall. Don't expect people to never flash through or just walk out because there's a smoke there.
- You need to play angles where you can't be easily traded, getting on kill and dying especially on defense doesn't always work. You're exchanging a ton of map control for one player. Also, if you're the site anchor, (the person alone on site where your team is generally defending a different part of the map) try to just play for one kill but most importantly stay alive for your teammates to run in to flood site. Hide in a cypher cage or play off of your killjoy mollies to block different angles to focus one fight at a time, and don't get crunched in two seconds by just holding main.
- Kill trading is extremely important, you should generally try to swing as soon as your teammate gets contact

Diamond:

- Positioning is really bad. If you're not able to easy escape and can be cleared easily by enemy utility, pick a different spot.
- If someone breaks a drone the minute you start using it, they're very obviously breaking it so you don't see something like an awp or someone else playing close with a shotgun, or so you don't see that killjoy's setup is there.
- Utility usage is generally poorly timed and poorly placed, I see a lot of Killjoy players not utilizing swarms on attack, Sage not using slows on attack, etc.
- You try the same things over and over again, and don't pay attention to the other team's quirks/playstyle. This is what "studying" in pro matches is, (to an extreme level) they adjust their strategy based on how the other team plays. There is always a better way to approach your hold/attack.

Ascendant-Immortal 2:

- I'd say this is where the game gets very hard to improve at and is where the most people will either get stuck forever or will take the longest time for them to get out of, it's a very long grind out of here.
- There are two types of people in Ascendant: the cerebral players with bad aim, and the opposite. If you don't make a solid effort to work on both things, this is where you will end up for a long time.
- Reading your opponents and potential outplays before they happen is incredibly important. Expect your enemy to know what you're doing. They've mastered the basic fundamentals of the game at this point and know what you can do. Don't run the same thing multiple rounds in a row, and try to read the enemy team's macro play in between rounds. You should be creating setups with your different teammates to counter the utility the enemy is using. Don't be afraid to ask for help, just don't be a jerk or too commanding about it.
- STOP leaving your teammates to die just to play lineups or something like that (they should be a last line of defense, some kind of a get-out-of-jail card, and sometimes you're going to have to have a read on what the other team is watching or knows while you're lurking and you're going to have to knife out and sprint through dangerous parts of the map to actually get behind them.
- Say everything you're going to do and use a few seconds before it happens so people are on the same page with you. You can't do it all yourself.
- Make your teammates comfortable. If they don't like a play, don't run it. If they're doing something sub-optimal regularly suggest something else.
- You're going to have to ramp up your aim training and stuff like that dramatically if you seriously want to improve. Playing slightly smarter than people isn't going to work and you can't just crouch spray every fight with god-awful aim anymore.
- Stop being afraid to just get on site. I don't know what happens between the ranks but for some reason everyone's super afraid in the lower ranks, insanely confident in the middle, and afraid in the high ranks again. Nobody seems to know when you're supposed to just run in until high immortal/radiant.
- Be aware of people contacting sites. I coach my Ascendant friends sometimes and I notice they just like to stare at angles for 45 seconds and then they get contacted and exploded on and get destroyed. Be info peeking when you need to and ready to back off.
- If you don't IGL your games insanely hard you're going to lose. Simple.
- You absolutely have to get used to countering an awp in this rank, use your utility and be aware of powerful lines the awper could have. Sometimes I will literally jumpspot angles in the middle of an execute expecting an awp there.
- Know when people are going to normal peek vs. wide swing. Sometimes crosshair placement is more broken in these ranks than it is in Iron.
- Might need to start VOD reviewing yourself when you get here. I've personally never watched one of my own games but I know that off of anecdotes from other people it's particularly hard to know what you're doing wrong once you get here
- Something I learned when I was in this elo is that you need to be playing for map control a lot more often. I've developed my own saying that "They always re-hit in ranked". Basically what this means is that people will be ready to rush a site and burn everything they have in two seconds to be shut down by nothing but a Brimstone molly. Then they have nothing to re-clear the rest of the map with and think they're geniuses for cutting noise and then hitting site again. It's painfully obvious a lot of the time and generally if you're cutting noise and then re-hitting in your match is because you made a mistake in the pre-round call. Fix it.
- Learn angle advantage and minmax it as much as possible

Past this I'm not sure I'm qualified to give generalized tips PLUS most people have everything down and you have to work on super tiny stuff, you need to VOD review yourself or just grind it out and practice what you're good at at this point. I'm giving you guys tips on what helped me personally and most of these are mentality and other little stuff and not actual gameplay related.

Immortal 3+:
- IGL your games or you won't win
- Pick one thing and get super good at it.
- The mental game here is incredibly tough. It's very hard to stay motivated. There are no real milestones between Immortal 3 and radiant other than arbitrary "300 rr, 400 rr" stuff like that. I've lost motivation and wanted to quit many times, you can't give up. I think at this point you have to just have to have that obsession with the game and want to win more than anyone else. I think the skill gap between Immortal 1 and Radiant is almost as big as the jump from Diamond 1 to Immortal. Despite it having way less players, making progress is extremely slow.
- You need to play to absolutely every single tiny advantage you can possibly get
- Everyone in this rank has somewhat close skill in aiming, it's very confidence dependent
- I fixed my posture and height regarding my desk and I think it helped tremendously. There are some videos I will reference below that I think seriously help.
- Abuse every gun you can and don't be afraid to awp on something stupid like Killjoy
- Make setups with your different teammates every round, it's incredibly helpful.
- Don't do it in a way where you let them run in and die, but baiting your teammates to trade them is something I found insanely helpful
- If your team is getting rolled and you really need to frag out to win, I sometimes will just sit in spawn and fast rotate to where any action is immediately
- Be aware of potential outplays to what you're doing ahead of time and be ready and adjust for it before you get punished
- Expect your teammates to be terrible and expect the other team to be geniuses
- Make calculated guesses, a quick example I can think of off the top of my head is how a lot of awpers will peek cat (defense) on ascent and if they get a comm that the enemy is B, there will be no one top mid and they don't even look there and just hold tiles and contain B main. Something I had to learn is that playing too perfectly just doesn't work sometimes and you have to make educated guesses on the enemy setup off of what you're seeing.
- SMOKE THE BOMB IN RETAKES, NOT MAIN. PLEASE. PLEASE. PLEASE.
- If you're making a play where you need to break dart or a drone or something, you need to have been breaking said utility the entire game or it makes it very obvious that you've changed your setup
- Basic bait plays don't work anymore
- Sometimes you just get outplayed and didn't do anything wrong.
- I am someone who I think is extremely untalented with aiming. I have hundreds of hours in aim trainers and around 2500 deathmatches played. I think abusing low sensitivity is an underrated tip and a broken way to aim in this rank. At one point I was using 0.15 on 800. The reason was because it made micro-adjusting incredibly easier and the only reason I stopped is because it was a bit difficult to turn flashes sometimes and it just didn't work for duelist which is what I want to pursue in the future. It was fine when I was one-tricking killjoy for a week though! I'm on 0.3 800 which I still know is super low and I think people handicap themselves playing on anything higher than what the absolute minimum they can use is.

Good resources for improving:
Good posture while playing
Good Mental/Tilt (This video is actually for Overwatch but literally everything also applies to Valorant)
Aim Lab
Check the VCT schedule and watch upcoming matches to learn decision making and setups from pros
Watching skilled Twitch streamers can be really good and is basically free pro gameplay you can watch. The only thing I'd recommend is that you don't watch someone that typically plays for content and focuses on good decision making and play.
Woohoojin YouTube channel, he's a Valorant coach that I think does a great job and gives guides for free. You don't personally need coaching in my opinion unless you've been stuck for a super long time, you can just watch VODs from people that are in the same rank as you

I wrote this all in one short sitting and I'm sure I missed stuff so if you think of anything to add or if I do I'll make sure to add it. Thanks