We were taught to place a small crop infront of our elbows and behind our backs so they keep still and jump small so that we keep our elbows in and jump bigger when we are out of the habit and don't need the crop to help

I agree with Kareen, just think many times about it, every time when you jump! Try to relax your shoulders, and follow your horse's movement after several times, that's going to be your all body which is going to adapt with your new position. I've had the same problem, and you'll see how much easier it is :)

I don't think there're some tips about it, just think about it until that's a reflex! Tell yourself "elbows along the body" every time you're riding!