I worked (on site, building stuff) for a builder, and that works. I knew nothing when I started and earned an amount appropriate to that, but learned a lot. It's been a long time, though, and I now have to refer to the internet and such when I want to remember how to do anything ...
Assuming that's not an option (the "work for" bit, not the "refer to the internet bit!") and depending where you live and what resources are available to you, you could do worse than to volunteer for Habitat for Humanity (or similar). In my parts if you do this on weekends, you are part of a large crew doing basically grunt work (nailing, painting), but you still get a chance to see a house as it's being put together, which could be useful as a starting point. Better would be (at least around my home area) if you could volunteer even a few weekdays now and then; here, former professionals (retirees) often go in and put the more expert work (wiring, plumbing, trim carpentry) in on those days, when the site is quieter. In my experience they're working for fun and enjoy showing fellow volunteers how to do stuff, plus can be a good network to get connected to if, for example, you want reasonably expert advice (or help) on a project.