Ok, I didn't read the other posts but..
Heels DOWN!! :)
When you go over the jump your basically over exaggerating your 2 point position + giving with your hands. Make sure you look up to where you want to go. You stand up slightly in your stirrups, fold at the hips and push your bum to the BACK of the saddle.
Pushing your bum back will help you get you balance back to your centre of gravity when you land, try not to lean forwards too much, you don't need to over small sized jumps as long as you get off of their baack.
When I jump, I think about standing up and pushing my bum alllllllllll the way back. And it makes it to where I want it most of the time