It helped me to do this training plus leg strengthening (squats, lunge jumps, etc.): stand on my bed, jump, keep my legs tight, hips forward and land on the bed with my back straight. It's like landing in the "pencil" position. You know the pencil when you do it off the diving board. It helped me realize that when I actually did the handspring, I was going to have to keep my hip bones forward and my back arched to prevent me from landing my hands where my feet started (it's called a term, but I forgot, like "under" something, IDK) Then, I did it on the trampoline and perfected it on the trampoline. I focused on "whipping" my legs back. The ground doesn't give like the trampoline does, so mats are really helpful, plus spotters when you start trying it on the ground. Always use spotters. Stay safe!
if you have a trampoline go n it and put your hands up as your going to do a back handspring and fall back 10 times,then go inside and do a handstand on the wall and walk back to be in a brige then stand up then try to jump and do a bridge then go on your trampoline and jump a bridge and and jump up and you have a back handspring