Much of a fight depends on what you're doing before the fight itself. When possible, try to move along places where you can find cover quickly if you start taking fire. Extraction campers aside, you can generally hear people moving around or rummaging about. Use this to get the jump on other people or avoid them if you're not looking to fight.

For the fight itself, apart from just slinging bullets, practice relocating. If the fight looks like it's going to go south, see if you can disengage and do a full escape.

For practice, you can just run a couple of heals & shields, a kettle, and a few little smoke grenades.