I never did any C64 programming when I was a kid. Hearing the Commander X16 might be ready for manufacturing soon, and it being C64 BASIC compatible (except POKEs), I decided to go through some old guides for the C64 but used the X16 emulator to do them. My absolute favorite was a course originally on VHS "Commodore 64 Introduction to Programming" I found on YouTube, there's 2 levels[0][1].

[0]https://www.youtube.com/watch?v=h3bDa5z_B1M [1]https://www.youtube.com/watch?v=iJDYoVgrtOs