Use gyro, if you aren't already. If you can't use it for health reasons then thats understandable. Gyro improves this game a lot imo, it will take time but improvement will soon follow.

try jumping while shooting in a 1v1 (better chance for survival)

Look up videos explaining weapon types and what maps work best for them, and videos explaining gear abilitys and which ones work best for each mode, but most importantly is jut getting experience finding your own playstyle, mess around with different weapons and gear builds! :3

Try different weapons,find one or maybe more that you feel comfortable with

Get good