I only use the cannons for the finishing blow. First i use the MGs at long range to force them to evade, turn and bleed some speed, then as i get in closer i keep shooting with the MGs.
If by that point they are not done for (the MGs are actually pretty good, i get a lot of pilot kills with them if shooting with a slight angle off), i will just give them 2-3 rounds of cannon at point blank range to finish them off and zoom back up, so that i won't have to come back down again to finish them off.
Generally speaking, i fly in lag pursuit if i even turn at all (i point my nose behind their tail) to conserve my energy. Then, when i get close i switch to lead pursuit but i don't "force" it with high G maneuvers.
I just maneuver in a way that will put me in front of their projected flight path instead of trying to follow their every step. When the range is sufficiently close, this mostly means using slightly out of plane maneuvers (high or low yo-yo) to help me "cut in" in front of them.
At some point they don't have enough time or energy to make a rapid reversal and they will surely cross my firing line, so i just put the gunsight ahead of them and a give a small squeeze of the trigger. Works like a charm.