Definitely take the armorer's course, it's a lot of fun and there are typically a couple in the mid-cities/fort worth area each year. https://www.glocktraining.com/ Only requirement is to be a GSSF member if you're not already.
As far as materials, there isn't really a "must have" - Glock's are very simple. The armorer's manual is useful and surprisingly small. YouTube will have everything you need but there is a lot of bad ideas and flat out wrong information out there so watch with a critical eye.
Scootch00's detail disassembly videos are pretty good