Take a look at this post: Form Over Fences
And...here's another HUGE tip that goes along with letting the horse jump to you:
When jumping, your hip angle should CLOSE and push your Buttocks BACK towards the rear of the saddle. Your seat, in this two point position should JUST clear the saddle by an inch or two. When the horse jumps his natural thrust will make sure that you are high enough out of the saddle for the size jump.
Nobody EVER told me this. I had 2 trainers who both had many successful riders...or so I thought since neither of them ever cared to tell me this tid bit of info from the beginning. Who knows what I would think if I saw their students jump now. I thought a release was to OPEN my hip angle and lay on the horse's neck to give slack and it is not. That is a common mistake.