Get to know your aircraft thoroughly.
Then master basic and advanced flight/aerobatic flight maneuvers, ie Split-S, Immelman, Yo-Yo's, Scissors and all the rest. Get comfortable flying in a 3D environment whilst mastering aerobatics. Once done, only then start concentrating on the principles of combat.
Aerial Combat is after all aerial ballet. If you cannot keep a step then you're just gonna end up twisting an ankle and hurting yourself every time.