Been a few threads about trampoline training in the past. Have been taking a tramp class at a gymnastics place called Twist-n-U in Lake Elsinore. The owner and several coaches are also wakeboarders (VERY GOOD wakeboarders). They have set up boardsport oriented tramp classes. Have awesome setup including standard rectangular tramp, superbounce rectangular tramp (you bounce twice as high!), handles, Guru boards, foam pit off of the superbounce, spotting harness, and much more. I'm in the adult class, having way too much fun. Occasional appearances by Rickey G. and Randall H. We always warm up/stretch before. Had only a backflip going into classes, now have back flip, front flip, side flip (a kind of off-axis flip), no bounce front and back flips, back flip with a half twist, and a double front into the foam pit. Has helped my riding tremedously (waiting for pop, waiting for peak rotation, air awareness, confidence). Excellent cardio workout, can't say enough good things about these classes.
http://www.twistnu.com