How do you find high-quality materials for self-study?

Web dev.

I subscribe to Frontendmasters.com

It isn't my only source but it is constantly very good.

I've only been coding professionally for a little over a year and that realization when I figure out that something I found online was written by someone with just as much clue as me is really frustrating. I'm willing to pay to limit those issues.

Amazon reviews for textbooks are, surprisingly, great indicator of material quality.

Coursera works well. I use libgen if need to study something in a more niche field