Murphy's Law of Paintball combat Don't look conspicuous - it draws fire. If your attack is going really well it's an ambush. No plan survives the first contact intact. Friendly fire - isn't. Anything you do can get you shot - including nothing.
Professional players are predicatable but the world is full of amateurs.
When you have have taken an area, don't forget to tell the other team. Tracers work both ways. When in doubt, empty your hopper. Never hide behind a tree thinner than you are. The only thing more accurate than incoming enemy fire is friendly fire.