When I was teaching rolls in AKK, I would have people start on the shoulder they were using for the roll. So for example, right shoulder roll:
Start with right side of head, right shoulder, right knee and ball of right foot touching the ground. Left leg is off the ground in a "chambered" position. Right arm is palm-up, pointing down the body towards your feet.
Slowly push off your right foot, lifting your left leg over and past your shoulders. Keeping your legs tucked in tight, let the left leg fall forward with the right leg following directly. Keep the left leg tucked in as it hits the ground, and try to land on the right foot.
Gradually increase your starting height, and voila.