I just went through this and finally got my eq over jumps to not look like a sack of potatoes. One thing I did was get someone to video my jumps and I would look back at them after I took them and try to fix what I did wrong. I don't know why this worked so well for me, but it's worth a try.
My trainer suggested to me to stand on a stair or something you can put your heels down on and to practice pushing my seat back to ring a "bell", when keeping your back straight and moving your arms forward with each rep. Doing this will help your balance and will make this form your reflex. hope this helps!