Here are some vault drills posted by Gym Momentum. They have lots of other goodies, so check them out if you have some time.
I like the “slide” drill – I’d never seen it before! Works good pre-flight positioning and the push through the shoulders needed on a handspring vault. Plus, it looks fun! 🙂 I’d use this with my advanced kindergym kids or my upper level youth rec who are work on/towards handsprings.