My friend and I both picked the game back up recently and are playing with some other, more experienced players. They've been guiding us through the games, when to spend, when to save, how to push, smoke etc. I've been playing more sentinels (KJ and Sage) while he's been playing duelists. Sometimes I'd comment that we have no smokes and he'd bring up that all you really need is to be good at gun play, and not worry about everything else while I still think that having a good comp and paying attention to your econ is good, although I don't have enough knowledge or experience to really argue with him.

Am I wrong in this scenario and just focus on getting headshots in low ELO and leave everything else for the higher ranked players? How much does it really matter at lower ranks?