Riders underestimate how necessary it is to ride forward through turns to the jumps. Turns take away energy, can cause a serious lack of impulsion right in front of the jump. Here is an exercise to teach you how to create the *habit* of riding sufficiently forward through your turns to jumps.
You should feel like you have to ask your horse to stop, rather than simply "letting" him stop. If he stops when you let him, he is behind your leg.
To successfully maintain the elusive forward feeling hands, imagine that you are pushing a shopping cart as you ride forward into the bit.
Horses speak through their actions. Try to listen to what they are telling you.
Spend time on the basics, such as straightness and suppleness, and the more difficult movements will fall into place naturally.