What is the best way to rehab from a rotator cuff injury?

Rest: Most rotator cuff injuries resolve on its own without specific treatment. Many times it just takes 2-4 weeks for the muscle the recover and start working again. In the meantime, working on the shoulder blade back muscles can help to hold and stabilize the shoulder. This puts less strain on the healing rotator cuff.

Strengthening: Allow several days of relative rest after an injury, then gradually and progressively strengthen the muscles that form the rotator cuff. These muscles are those that turn your forearm in and out when your elbow is held in a fixed location. Elastic bands are very useful for this type of rehab.

Rehab unless torn: For an injury to the rotator cuff which is just inflammed, it wll likely calm down with nsaids, ice and possible cortisone shot. Rehab will help with increasing motion and strength of the rotator cuff. If there is tearing or ac impingement as the underlying cause, you might need surgery.