Don't rush the matches. Take your time to figure out your strat on T side. Work together, make sure you know smokes and flashes. know how to retake.
Thats a good chunk of how to win an ACTUAL competitive CS game.
Tap, don't spray. Pistol round ct side keep distance and aim for the head with usp, no point in buying when you can one tap someone with what you got. Play safe and check corners.
Crosshair placement. Keep the crosshair at head level where enemies commonly hide. Smokes are useful and molotovs too. Learn how to throw nades over buildings and make them land in certain places. Learn all the flanks. Watch other pros play and analyze their gameplay
Learn Russian, only buy p90, rush b every time and don't forget to blast shitty music through your mic, the music will work in your advantage because if you can't hear them, they can't hear you.