When I first looked at these, it was hard to see what you were trying to trace because the muscles you're trying to draw are typically covered up by other muscles in the back, delts, traps, and latissimus dorsi in some references.. I would say that following a procedure of first identifying and drawing in the bony landmarks such as scapula, 7th cervical vertibrae, connection between scapula and clavicle (prominent bump) will help with placement of the teres major, teres minor, rhomboids, etc. Then figure out what goes on top of what. A good reference such as the one I use, "Anatomy for Sculptors - Understanding the Human Figure") is helpful, but you can also search images online for free. Since you're working digitally, take advantage of the layers.

Another one

Looks great to me! Those are some of the toughest muscles to get right for me.

Hello! Here goes: Anatomy - The rear delt goes *over* the infraspinatus, making the top portion not visible. If you still want an indication of the insertion of the infraspinatus I suggest making the lines less dark/visible. The bottom of the trapezius should be on top of the latissimus. Finally, the triangle of the trapezius isn't that big. Don't be discouraged, I like your drawings! Other - I suggest working on structure a bit more, ignore anatomy for a few seconds and just focus on the shape of the shoulder (it's 2D silhouette) and making it feel interesting. Keep at it! Nice work.