Know where your team is - If you have a hard time always following the pack, at least know where they are and what they’re doing. Those little white arrows are a huge help – they tell you where your teammates are and whether or not they’re in combat. A red ‘X’ means one of your teammates has just been downed - this is valuable information.
After an opponent has finished off one of your cohorts, not only has he probably let down his guard for a moment, but his shields are likely damaged. This is the time for you to toss a few grenades and jump in for the kill. Ambush baby!
Don’t call attention to yourself - If you stay near your team, you present the enemy with a dilemma: who to attack first? If you’re off by yourself firing missiles all over the place, however, you’re an easy and valuable target, and will likely be the subject of many beatings.
Tip: A missile pod and a good camping spot can rack up kills... and make you a popular target
Prepare to die – Sometimes, to get a kill, you’ve got to accept that you’re not going to live long enough to gloat. If you’re attacking an enemy and several more come at you, stay focused on your original target. If you make it out alive, run for cover to recharge, if not, at least you took one of them with you (oh, and try to leave your attackers an explosive gift before you go).
Just keep talking – You’re not always going to be on a team that likes to communicate, but it can be very helpful. If you grab the missile pod, for example, let your teammates know to stay behind you and provide support, keeping out of the way of your missiles. If your team isn't the cooperating type, fine, watch them bite the dust and then go in to clean up their leftovers. No one will mistake you for a "team player," but you'll get the kills.