Start with just standing and attempting to shift your weight (use a wall or chair if you need to) and ground solidly into your standing leg while keeping your hips as level as possible. Intensely activate your abdominals, kegel, and glutes for all of these, and keep your knees unlocked but straight. Then try tapping a foot ahead or behind you or to the side. If that is easy, pull the lifted leg around and push the toe into the ground in a half circle - really working the standing leg stabilizers/rotators, and all the abductors/extenders of the moving leg.