These are really old, but I found them very helpful for beginning cartooning years ago: http://karmatoons.com/drawing/drawing.htm

Drawing on the Right Side of the Brain, by Betty Edwards. Learning to draw is actually mostly about learning to see; not seeing the objects as we usually do, but seeing the light and shadow that form them.

Drawabox has some great exercises and starts by teaching the mechanical skills necessary for drawing.

https://drawabox.com/

andrew loomis has really helped me, search on archive.org, the books are not in copyright anymore..

Check out the Traditional Drawing list here: https://www.ctrlpaint.com/library/