A project on which I'm currently working involves a society at 1930s-level technology, wherein airships are a common means of transportation. I'm lucky enough to live close to one of the Goodyear blimp hangars. I'd done enough homework on airships that I was able to talk my way onto a blimp flight and even take the controls for a few minutes. Finally, and maybe most important, once you've done all your homework and settled down to write, omit anywhere between ninety and ninety-five percent of what you've learned. The trick is not to tell the reader everything there is to know about the world you've created.
Nothing makes the audience flee faster than huge expository lumps.
What you want to do is subtler. Suppose you know five hundred things about your world. You need to pick, say, twenty of them, and use those in such a way that they're not only telling in and of themselves but also create a certainty in the reader's mind that you know the other four hundred and eighty, too. A colleague of mine once remarked that writing alternate history is the most fun you can have with your clothes on. Maybe, maybe not.