Another valuable resource touching on the same topic: https://johnkcurriculum.blogspot.com/ The overarching theme is getting the most out of the medium and avoiding blandness and boring results.
When all the details came out of what he'd been doing to Robyn, Katie, and a long string of other women, all my art skills felt tainted and nasty.
I'd prefer to attach warnings to all mentions of his stuff, to help anyone looking to learn about drawing know what they are getting into.