Don't Leave Matches
If you grow frustrated, you might be tempted to leave a match. You don't want to do this. Even if you're getting clobbered, there's incentive to stick around.
If you leave during a match, you're going to miss out on a match bonus which nets you some additional experience points. You'll also lose out on the experience that you earned during the match. This is DICE's way of ensuring that most people stick it out until the end.
We say most because people still drop like flies when the going gets tough, particularly in the smaller game modes like Cargo.