MY EYES! MY EYES!
That was hmmmm Sensaur.
First off don't do ground flips on -9.82 gravity. Its just so easy... Try doing flips on -30 gravity. -30 gravity is used for realistic replays because it is much closer to real life gravity.
It was so stiff... you use some joints but then forget to change them. If you want to do a fast movement like contracting your elbows, only ever contract for 1 turn.
You can relax it after that. This works for everything, don't extend something for more than 1 turn (10 frames) and always remember that relax is your best friend.
There is no power in the jumps. When you jump, you jump from your hips, not your knees.
Dont just go in the air and then do nothing in the air for 500 frames. It makes you look like an object and not a person.
At the start when you jump, prepare for the jump. You want to relax a bit so that you fall down, then launch into the air.