Practice practice practice, Also:
what games are you trying to get better at?
FPS MOBA MMORPG?
first person shooters require good hand-eye cordination. So for me, I join private matches for a warm up (30 minutes) of testing sensitivity and setting it up just right so I can flick and aim where i instead to. Get used to the recoils in different guns and spend time reflecting on why you died, etc.
I also watch alot of streamers for meta game plays and mimic them to become better