Join Date: Aug 2009
Location: New South Wales, Australia
Maybe you should stop holding on. Even though you are getting practice, if you are relying on your hands for balance it might be harder to build the correct muscles and skills you need to balance.
Lean back, when unbalanced people tend to lean forward, but this doesn't help with your position. Push your weight down through your heels. Some people sort of move their body forward and back when sitting trot, others side to side.
Each horse has a different way of moving. Try riding horses with smoother paces until you are used to sitting.