Improving body stability while jumping

Do you have an exercise ball at home? If so, that could be very useful. I’d start by just working on balancing on it on your hands and knees. Then, when you have that down, try to rise so that you are just balancing on your knees - essentially kneeling on the ball.

(the more inflated the ball, the easier this is, so I recommend making sure your ball is completely inflated).