Spending a lot of time working on imbalances and doing corrective exercises probably isn't high on your list of favorite gym activities. You'd rather be lifting heavy stuff. But there are a few simple things you can do to help you avoid picking up silly injuries. This is one of those things.
A joint likes to be moved like a joint. There are no two ways about it, and ball and socket joints like your hips and shoulders joints love circles.
Simple movements for your shoulders in a quadruped position (all fours) work best – up, down, left and right, then in a smooth circular motion. The key here is to keep your elbows locked and still.
Do this every day and practice smooth fluid movement each time. If you feel any weird grinding or tightness, simply doing this exercise for a few weeks can help alleviate it. And if not, then it's time to work on other posture issues and get those sorted out.