playing on a team with like-minded people is one of the best ways to improve. scriming/learning the game as a team together makes it easier to coordinate and know what to do in whatever situation you find yourself in. it's much better to play with the same people all the time then playing pugs with random people (more practice obviously helps)
watching your own demos to try and understand the flow of the game figure out why the other team did something or why you died in a situation is also very helpful. (going over your demos with a teammate or a mentor from a higher division is even better)
actively think about what you are doing while you play.
play for the team not for your stats