I think the problem is learning to use what you have, NOT making things easier to cut the corners. All it takes is practice 
+1, use your plane's strengths to fight. And if you have a relative clue on the opposing plane's characteristics (ex. climb, speed, turn) you can use that against them. A plane that doesn't turn too well or speed, or climb too well is a whole 'nother ball game.
Some of the things I learned during my time in the P-39 was
1. Choose your fight, don't just dive at the first enemy con you see, always look around, to make sure there won't be anyone else coming after you. (I always could work well against a turner and a BnZ'er during a 2 on 1 if I had some good alt. Those are usually the ones I can fly away from.)
2. Don't run, no use in trying.
3. Try to stay out of the huge furballs. Only thing that'll happen to you is you'll just die quickly. I usually seemed to work better in the medium and small fights in the P-39.