What are the best free ETA learning resources you’ve found?

I’m in the early stages of exploring ETA and want to absorb as much as I can without immediately jumping into paid programs. For those of you who have been down this road already: What free resources (podcasts, articles, blogs, newsletters, videos, frameworks, etc.) helped you most when starting out? Are there any “hidden gems” that don’t get mentioned as often? If you had to recommend just one or two resources to someone beginning their ETA journey, what would they be? I’d love to create a master list of high-quality free learning tools that others in the community can benefit from as well. Looking forward to your thoughts—thanks in advance for sharing!