Ok.. My cp wanted a BHS really early too. Her coaches told me if she insisted on it, then she needed to be able to hold a perfect handstand for like 30 seconds and have a backwalkover first. She was persistent enough to meet the requirements, and had a RO BHS when she was a little over 5. Please take my advice! I have a highly motivated young athlete, who doesn't like boundaries and hearing no. Conditioning is essential to good technique. If she wants skills quickly, she better be super strong!! My cp is level 5 working on elite combo passes, and still has to work on basics. I think that is partially to blame on the fact that her technique varies, because she rushed through getting her basic skills......
But to answer you question. Handstands will help. Lots and lots of handstands....