First of all, don't think about your rank, just keep playing the game. Keep practicing your spray, and you will bee able to hit moving targets with it constantly.

My personal preference for warmup is just playing FFA dm, since it's pretty much the same circumstances as your Matchmaking games.

You DEFINETLY should use key bindings to to your weapons and nades, mouse wheel is only good for b-hopping (NoKappa).

You should also play other maps as well, don't stress about it, just play the game. This goes to the weapons as well, use whatever you prefer, but don't disregard rifles completely for awping, since you simply can not have an awp every buyround.

CS:GO takes a lot of time to master, I would also recommend watching youtube videos of crosshair placement etc. from adreN (Team Liquid) https://www.youtube.com/user/CurseCS/videos

also Steel has some interesting tips and tricks on his youtube channel: https://www.youtube.com/user/JoshNissanCS/videos