This is an interesting one that I really had to think out. For me, in no specific order:
- Google. Simple as that.
- My online guys. If I'm on a forum long enough, I'll identify various posters that are extremely knowledgeable. Some of these guys I know personally, some I've never interacted with. Querying them for info can be anything from sending a personal email, to directing a question to them in a thread, to including their username in a Google search.
- My offline guys. These are people I know personally, not in cyberspace, but in meatspace. Mostly older guys, some in my neighborhood, some in the nearby area, some who work at places like the hardware store or the lumber yard. These are generally people who rarely, if ever, use the internet. There is a really smart old hotrodder in the next canyon over. He doesn't own a computer, and I'm pretty sure he's never been online. He has this joke I've heard a million times. When anyone mentions the internet, he says: "I love the web. I used to have one of the oldest 'web' sites around, until I took it down..." Then he points to the corner of the ceiling and says:
"...with a broom!"
- Books. Still beats the internet for lots of topics.
- My mistakes. I have a go-to response I say when I get a compliment on something I've made, built, cooked, etc. I say: "Thank you. My secret is years of screwing up." This usually gets a laugh, and it's very true. A good screwup, followed a good analysis of the screwup, generally yields a lot of knowledge.