This community is primarily structured around the sort of subjects you would see in an academic setting, but learning skills is absolutely within the scope of this community. If you have any, please consider commenting with free resources and advice for things like playing an instrument, learning a language, woodworking, etc.
The library: It’s nothing sexy but I’ve always had luck going to the library and grabbing all of the books off the shelf on the subject I’m learning. I then sit at a table and quickly scan through the stack. After finding the ones that seem the most valuable of the lot I take those home and work through them. I was lucky to live in a major city so my library had a ton of content.