Way back in 1958, four Disney artists demonstrate their various painting techniques through a nature study.
We can still learn a lot from this.
I found the approach of these working artists, and their methods and materials (oil paint and lighter fluid? yikes!) to be most interesting.
The Art Spirit by Robert Henri is a classic and most working artists I know have read it at one time or another.
This book invites reading time and time again. It brings us back to the principles. The value of things. Right thinking. Relationships. Some things never change.