Keep your SA about you. Never become target fixated, and always keep your E. Especially in a massive furball. When you do engage take it vertical (if your plane allows) then fall back in to the Mess/opponent and rebuild your E in the process. If you get slow, you will get picked. If you stay fast but lack SA you will get picked/ho'd/hammered in to the ground. (unless in a 51, then just run like H3ll and laugh) Deflection shooting or making them knife out in front of you for a snap shot is the best way to kill in a furball. You saddle up on your targets 6 for -any- length of time and your asking to be towered out A.S.A.P.
Near the most important piece of all is, find a good buddy to fly wing. 2 sets of eyes always trumps the lonely pair.