In 1973, Sam Blumenfeld wrote How to Tutor. It was written to help parents start private schools and/or homeschool their children. A PDF version of the book is available here http://campconstitution.net/sam-blumenfeld-archive/
And here is a link to an audio version of his presentation made in the early 1990s:
https://www.podomatic.com/podcasts/shurtleffhal/episodes/2021-03-12T07_05_42-08_00