It basically comes down to this. Know your plane well....know your enemies plane BETTER. Fight to your strengths, avoid fighting into your weaknesses while doing everything you can to entice the enemy into making a tactical mistake (if not a real one) and capitalize on that....ie:
A P51 is fighting a Spit. THe P51 should avoid sharp and/or maintained turns. The P51 should also avoid long high angle (3K or more) climbs.
Th 51 should try and force:
Long gradual turns with no or slow climbs
Zoom climbs near 90º, using its superior speed once you determin your speed is higher than the spits
Any high speed manuvers, including high down angle that play into the 51s strength and works into the spits weaknesses at high speed.