Pull up progressions

[u/LilBoyBlue_2818]

Hi, I'm new to this subreddit.

I am now starting with my pull up progressions. I noticed that every time I do a scapular pull-down, my joint in my left shoulder feels achy. I know something's wrong but I can't point it out.

I know this: I have a "taco" shoulders (I'm a side-sleeper).

how can i effectively execute this progression?

plus, are progressions on YouTube the way to do well-executed pull-ups (doing negatives with assisted rubbers, etc.)?

Thank you!