Rotator Cuff Pull
You'll need to lie down on either a table or a bed. Let your shoulder and arm hang over the side. Take the weight in your and and bend your elbow so that the weight is level with your face. Slowly lower the weight down to where your arm is vertically extended towards the ground and then pull the weight back up, bending the elbow as you go. Repeat this exercise until the shoulder is tired then switch arms. Regardless of whether you are rehabilitating one rotator cuff or both, you need to work both sides so that you remain symmetrical.
Lay on your right side (or the uninjured side of your body), right arm extended above your head with a rolled-up towel underneath your armpit. Take the dumbbell in your left hand, elbow at a 90 degree angle so that your forearm is perpendicular to your body. Rest the weight on the ground in front of you. Slowly bring the weight up so that your forearm is horizontal and then back down. Do this until your shoulder gets tired. If possible, switch over and do the right rotator cuff as well.
Lay on the left side of your body (or whichever side is injured). Make sure that your shoulder isn't in pain when you do this movement. If it is, move on to the next exercise. Your upper arm should run down your body, your lower arm bent 90 degrees at the elbow with the weight in your hand. Slowly bring the weight towards your upper arm and then back down to the ground. Repeat this until the rotator cuff is tired and then switch sides.
Stand up and take a dumbbell in either hand. Slowly lift both arms out away from the body turning the front of the weights down with your forearms as you go. Go until your arms are at a 45 degree angle from your body then bring the weights back down to the starting position. Once again, do these until your shoulders are tired.