I'm just a casual player, only lvl 25 and I haven't even played a single ranked match, but I do still want to improve.

A lot of guides I keep seeing for the agents I use (Cypher (his cages), Viper, Sova) make frequent mentions of their lineups, however there are so many that I can't even remember one from the sheer information overload of lineup compilations.

Are lineups essential to being good at this game, or is it just an extra bonus once you've already become good?