Wall Tricep Stretch
This is a great tricep stretch, but it might be problematic if you have shoulder problems. Start facing a wall and raise the arm you want to stretch above your head. Place your elbow against the wall as high as you can comfortably and relax your arm and shoulder as much as possible.
Begin the actual stretch by letting your elbow bend so your hand drops down towards your neck/back. If your tricep is tight, this could be enough of a stretch, but you can increase the intensity by grabbing the wrist of your stretching arm with your other hand. Then push down so your hand moves closer to your shoulder.
If you can’t be in this position without shoulder discomfort, try doing the stretch holding your elbow straight out in front of you. If your elbow is below shoulder height, it won’t put nearly as much stress on your shoulder, but the stretch may not be as effective. You can use the same technique of pushing your wrist down with your other hand to increase the stretch.