First, make sure that you get a good push off the ground with your legs. And do some on the trampoline at the gym by yourself, if the coach says your ready. Or, you could do them on a big, squishy mat with the coach standing there if they say it is okay. Just make sure you keep your arms by your ears and straight! Good luck!
lets see i got in the pool and did a kazillion. have a coach spot you doing one up onto a panel mat/four incher/eight incher so you get more power when you go back on to a flat surface. (feet on floor ahnds on mat). um tramp is a good thing always. repition is always good. hope that helps