It really depends on what the topic is. I always hit Google or DuckDuckGo first. Most of the time, I can find all of the information I need after a few tweaked searches. If not, the information I probably need is in a book, so I find a book. The great thing about nonfiction books is that the authors love to talk about other authors and their books. So there's more books I can read on the subject.
If it's tech related, or something hands-on (like cooking, gardening, auto repair, etc.) I like to just jump in head first and get my hands dirty as soon as possible, reading up on tips and techniques here and there as I go. Youtube is great for these. There's often a ten minute video with exactly the information I need.