What you do depends on what you're flying and what the other guy is flying. Once you know what your plane can do and what the other guy's plane can do, you'll have a better idea of your options.
To get this sort of aircraft knowledge, you should try to fly the more popular airplanes a few times. One thing I did was "fly the plane that last shot me down". I got a lot of stick time in the LA-7, Spitfire IX, P-51D, and Typhoon this way (I refuse to fly the N1K2). You might also try flying the "second tier" planes, such as the Yak9U, P-51B, FM2, Zero, Spitfire V, F6F, F4U, 190A5, A8, D9, 109F, G2, G6, G10, and Hurricane just to put yourself at a disadvantage a few times and try to work your mad pilot skillz (its also a good way to build a lot of perk points).
There is no specific maneuver that can save your bacon every time, though I have had some success by staying fast in the fast planes, and using rudder-assisted turns in the slow planes. In a fast plane, I never follow a guy's turn unless I know I can beat him slow. Once he goes into his break turn, I go into a climb and set myself up for another run from above his head. The more he turns, the slower he'll get while I climb up and stay fast. Eventually he'll end up on the deck and slow, which will result in either him flying straight and level to get his airspeed back or crashing into the ground in a stall.
If I'm jumped by a fast plane and I'm in a slow plane, I'll turn and try to draw him into the turn fight, too. The slower the fight gets, the more the advantage will shift to me. If he doesn't take the bait, then I go nose-down and try to equalize our airspeeds, then try to get him to black out in a hard turn, change direction of my path, and get away while he's still trying to recover from his black out.
One maneuver I use, and its specific to the Mustangs and Corsairs, is the high-speed stall. If the guy is coming in behind me and is faster than me, I'll stall my Mustang so that it tumbles through the air. Of course, this can sometimes come back to bite me if I can't recover in time. It also bleeds a lot of speed, unfortunately. Still, it will cause your flight path to be eratic, so your attacker will either have to spray in your general direction or break off his attack and wait for you to recover. Last night I was flying a P-51B and was bounced by an LA-7. I stalled the plane and went nose-down to recover. Meanwhile, the LA-7 climbed above me and went straight down to try an kill me. As I recovered low and slow, he went speeding past me and augered into the ground.
Anyway, those are some ideas you might find useful.
