I absolutely second both of these. I have been suffering with a shoulder issue for the past 9 months. Physio didn't help. Since i injured it, something has changed in my shoulder; it now clicks and cracks in ranges of motion which it never did before.
Passive hanging, followed by straight arm active hangs (almost daily) for time have worked wonders. Passive hangs will stretch the lats and open up space in between the humerus and the acromion allowing more space for the tendon to pass through decreasing chances of impingement, whilst active hangs will strengthen all of those muscles that hold your shoulder blades in place. You can then work up to active hangs with hollow body, then active hangs in an L sit, etc.
You also might be surprised to find how stiff your scapula are when you first try this. I will specify the only thing that should be moving is your scapula - just pull your shoulder blades down, but keep your elbows locked out - this is an important point. You might feel like you can't do this much without bending your elbows, but that's just because you don't have good scapula control at the moment... At least that was the case with me.
Since I have focused on doing them strictly with elbows locked out, my shoulders have experience a huge improvement in stability and scapula control and a decrease in pain. Friends have commented on my posture, too.