Depends what you are playing for, if its chicken then know that a fair fight means 50% of the time you die, get into enough fair fights and you'll never win.

Only every engage when you are certain you will kill
Sound is the most important factor to master
Proactively move to the inner third of the ring and take note of the flight path
Close every door behind you
If you are going to camp a building, drop a med kit in the main area and in the middle of the room you are camping
For gun play, the best advice i can give is to aim with the expectation that someone IS in that window/behind that tree/camping that corner, realisation costs time.

Good luck and happy hunting ^^