These are the best resources I've ever seen on how to study drawing. I've seen too many bad tutorials / books / courses and I hope I can help you avoid wasting time on those too.
Most important videos:
Krenz Cushart: (turn on subtitles)
https://youtu.be/kbKqIJcIUCw
https://youtu.be/dgjx6y6B_G8
https://youtu.be/594WhCme2pQ
(importance of accuracy and master copies)
(This is the best lecture series to show anyone who doubts that accurate drawing is important for people who want to draw from imagination.)