i'd like to ask how old you are before i answer that. for now ill assume you are a developed person who has been training with your athletics club.

key factors to a successful high jump are; co-ordination, timing, and explosive muscle fibres in the leg muscles.

for a more accurate answer ask your coach, but i would advise you on a couple of things.

power training: weights 3 or 4 sets of 3 reps (squats lunges and jumping squats), plyometrics drills such as hurdle jumping (one leg much preferably)

visual training: for mental readiness. remember ur perfect jump that u nailed once and run throught it in your head. good for posistive thinking!

practice: just as i said, get down the track and go through your drills and listen to your coach!!! good luck, chris.