Reaching overhead uses two muscle systems. A person can avoid overhead reaching by using a reacher when necessary and by not placing things above the shoulders. Find other activities that do not involve shoulder use. Slings don't usually work too well because they hang from your neck. I prefer to use a gunslinger apparatus to help support arm and shoulder.
Some patients use a fannypack under the arm for support.
When working at a desk, do not lean forward to do your work. Bring your work to you. Feel the aches and pains. Then do something about it. I do not recommend cold packs but prefer using ice massage for only two minutes.