1.  HANDSTANDS. Think of your hands as a baby's feet.  When you tumble, you will be learning to put weight on your hands, like a baby learns to walk and put weight on his feet.  That is why your wrists will hurt when you begin taking gymnastics.  You must be patient as you learn to hold more of you weight on your wrists.  **Do as many handstands as you can do, wherever you can do them.  Doing back handsprings requires that a human body go upside down, and support the entire body weight with a force of up to twice the weight of the body on the hands.  The better you get at doing back handsprings, the less weight you will have coming down on your wrists.  This is why handstands work, and lead to the learning of the skill.  This is why we do so many of them, even AFTER you learn a back handspring.
2.  Weights: Get a 5 pound weight, and simply lift it slowly above your head with straight arms 50 times a night.
3.  Back bends: Most people can’t do a back handspring because they lack a great deal of flexibility in their arms and shoulders.  Back bends aren’t fun for older girls, but if they will do a few a week, they will certainly see a difference. 
4.  “Banana stretch,” for one minute each day, with a partner.  This would be equivalent to doing several back bends.
5.  Push ups: Just 5 GOOD ones per day would make a world of difference.
6.  Sit ups: Just 50 each day, every other day, or even twice a week outside of practice would also make a world of difference.
7.  “Doggies:” 100 with each leg  (these are best if wearing ankle weights.)
8.  Toe Raises: 100 (even better if holding a 5 pound weight.)
9.  Heel stretches:  10 with each leg
10.  Splits - left one minute, right one minute.