Stretching is one of the most basic ways to start to rejuvenate an injured rotator cuff. If things hurt when you're stretching, you're pushing it too hard. Slight discomfort is OK, but if you feel actual pain, you should back off and consult your doctor. The best way to stretch your shoulder ligaments and muscles is to use a wall. Position your body so you can feel the stretch in your shoulder area when you put your hand on the wall. Most wall stretching exercises occur with your hand palm or back flattened against the wall.
Resistance bands are a low-impact alternative to weights and they're easy to use. You can tie them to door knobs, wrap them over door tops or around banisters and rails. You also can wrap a resistance band around your body or just hold it in your hands and use that for resistance. Presses and flys are the best exercises for strengthening your shoulder using resistance bands. Tie off the band so it is at elbow level or lower, then raise your arms straight up to do a press and out to the side to do a fly. If it hurts, back off it until there's no pain.
Barbells and dumbbells are the best way to build strength and muscle around your rotator cuff. The exercises, with the exception of the bench press, are the same ones that work best with a resistance band: presses and flys. Using a barbell or two dumbbells, start with your arms at your sides. For a press, slowly move the weight up your body so you are holding it over your head. Then bring it back down to shoulder level. Repeat as many times as you can. To do flys, you'll need two dumbbells. Start with your arms down at your sides and move your hands out, away from your body. Hold them out for a second and repeat.