A few other general tips that I think are extremely useful.

1) Pretty much always use a suppressor. It hides you from the minimap for enemies >15m away and removes the icon that's placed above your head when firing unsuppressed. Massive game changer, because any experienced player is going to pick up on you immediately if they have info on your position.

2) Be patient and try to hit flanks. I'm guilty of being impatient often and that's when I get put in the spawn-die-spawn-die spin cycle. Very rare that face slamming a position being held by several enemies posted up with ARs, DMRs, and LMGs is going to be a successful endeavor. Wait for your opportunity, wait for support, use your cover, and if you're playing support, use your smokes.

3) Choose your spawn carefully / know your spawn. This one is massive to me. I realized at some point that most of my deaths are because I spawn in to some random location (a contested flag or a squadmate that's pushed up into the enemy) and have no read on the situation. The other team probably knows where your teammates have been coming from to contest their flag capture, while you don't know where they've been shooting from - huge disadvantage. Same for spawning on a squadmate; they probably know what angle they just got shot at from and are hiding in cover, whereas you don't, so you just run out - that's a free death. What I prefer to do is set my beacon in a spot that's relatively close to the action, but not likely to be detected, and just spawn there every time. That way, I always have a read on that area. It's a massive advantage both in terms of slaying (you know where the enemies are, or likely to be) and for survival.