people are opportunistic.
when a player dies, most likely they (or their teammate) will want to pick up any power weapon they may have dropped. This is an excellent chance to get a jump on them and catch them off guard (again). Also, since when a teammate dies, we all know a appears over them, so this is pretty much telling the enemy where you are (unless you killed them long distance), so don’t be surprised seeing the other team come your way. That’s usually when a nearby teammate attacks in hope of finishing you off (they assume you are weakened, reloading, etc) so anticipate this.
Make noise.
people are for the most part, use their ears when playing. You can bait or distract people by things such as firing your weapon, setting off explosives, canceling ground pounds. The ground pound charge up sound is a dead give away. If you do it, some players freak out or will aggressively attack you. For example, If I know my enemy is around a corner, I jump in the air and cancel a ground pound. Usually the enemy runs around the corner thinking I’m going to miss when in fact I cancelled it and catch them off guard.
Another tip, You can charge the railgun (without firing) for as long as you want which makes a very distinctive noise. Constantly hearing this keeps the other team on their toes.
people like to rush
people like to rush power weapons and power ups at the start of the game and also when they see the respawn timer tick down. if you have grenades (splinter grenades work best), throw them at those power ups and power weapons, if they run over it (which they will), you’ll get an easy kill and the power weapon or power up. This is safer than rushing the power weapon hoping to grab it first or fighting over it. This is especially helpful if the enemy grabs the overshield since even though they grab it, they die before the overshield is added. A charged plasma pistol also works very well.
Those are some of my tips. Feel free to add your own!