Also, make sure to encourage movement (adults call it exercise, for kids is play). I used to be really clumsy as a kid before I got into sports as a late teenager.
Consider occupational therapy as well. It was very very helpful for my daughter, who was "behind the curve" with her gross motor skills. It's not just about increasing physical ability, either. Lack of core strength can affect the ability to sit still and focus as the body gets fatigued more easily.