There are no real trick, you canīt ged "rid" of blackouts. But they are the same for every pilots. If you enemy is really pulling at the same speed and turnrate as you, he will get the same blackout circle. The trick is not to completely blackout, just like you "ride" the stall in tight turns. But remember, the more Gs you pull, the more energy you will lose - the tightest turn is not always the best one.
But often it only seems that your enemy is turning at same speed & rate as you. An enemys speed is hard too judge sometimes especially minor differences. He may for example have cut the throttle, so he will lose speed rapidly and therefore being able to turn a bit harder than you.