1. Join a Kill Creek Elimination/Quarantine match. Go hide somewhere where you won't be seen for a while. Turn on Ghost Mode and head for the train in the middle. Open the door on both sides over and over while people are inside. When they try to close it back, open it back up right away. (My personal favorite)
2. Megakill/OPK/Remote Kill/Tele-Kill etc.. Pretty self-explanatory.
3. Voice Spammer. Very annoying and effective.
4. Crash games all day. Can be very rewarding.