For me, it was a little like starting a business in that I learned a lot of it on the fly. I did research before I quit but, as they say, "You don't know what you don't know." The first couple of years were just a learning experience in every sense. I had a handle on most of it, but there was always some question about taxes, or saving, or what to do with my time, or "working for fun" that would come up.
I say just relax. Understand the basics like insurance, minimum withdrawal, etc. which you really need to know and which you seem to already have a handle on, and deal with the rest of it as it comes along. You'll never have all of the answers. Even today, 11 years in, I'm still learning stuff. I just correct and improve as I go along.