Some good stuff written here from people who obviously know what they are talking about but................I would add just two or three points.
Brief VERY fully before you fly so that each knows EXACTLY what the other(s) are doing. Do NOT change anything in the air!
If you are still in a high state of practice don't go in close until you have perfected each and every manouvre.
Keep a steely eye on the point you chose on the aircraft you are formating on and remember to anticipate the throttle opening movements on inside and outside turns - you can lose position very quickly if you don't.