I am studying The artist's complete guide of facial expressions- Gary Faigin. Very slowly. So much information to digest. Between reading I try to practice in my sketchbook. I hope to get better in time, I had a lot of fun making these little drawings.
References: www.bodiesinmotion.photo/, friends, Facial expression of Mark Simon and some I couldn't find the source of. Promarkers and fineliners in my sketchbook.
Thank you for your reply. Nice to see what mood you're in.
The book is very helpful. It goes really deep. It feels like a goldmine to me, it really got me more into understanding relationships of muscles and expressions. I haven't finished it yet, but every page I learn something new and interesting. The book really goes deep and relates heavily to the anatomy of the muscles. Many, many drawn examples in the book and tips for rendering. I recommend it. It is more on accessible than e.g. Human Anatomy for artists from Eliot Goldfinger.