This!  Before I will let my guys make an attempt on snow they have to do 100 back flips on a tramp the week before.  34 tucks, 33 pikes, 33 layouts.  This helps them to get comfortable knowing that they can speed up or slow down their rotation.  Why people usually get hurt trying backs is that they keep looking up to the sky and never spot for their landing.  "Look for the ground, you'll get around; look at the sky, you're going to die".  Also, think about humping the sky!  Throw your hips up and then start looking for your landing.  Being a little on your tails is OK but trying to full on butter a back flip is bad.  You either smack your head on the back of the jump or you can't stop your rotation and land on your back if your lucky.  If you're not lucky you end up rotating another 180 and lawn dart.  Those that do that usually end up with a permanent new mode of transportation.