Writing almost any book—even if it’s fiction—is going to require some research. Research doesn’t just mean looking things up in books. There are a number of different ways to research. My personal favorite way to research is to go to a location I need to describe or put myself in a situation that I’m going to put one of my characters in. One of the scenes in Children of Abraham takes place on the Senate floor, so I went to Washington and got a pass from my congressman and watched the Senate and its proceedings. I got an entire chapter from that experience. I found out where the senators’ offices are in relationship to the Capitol. I was able to describe the buildings and the marble floors and what the offices looked like. You can put all of those descriptions in. (Of course, you always have to be careful that you’re not describing just for the sake of describing—everything should move the plot forward.)
Of course, sometimes you can’t physically go to a location you want to use. Then you use the internet. I had one scene set in Turkey in which a couple of characters meet for breakfast. I needed to know what was in a typical Turkish breakfast, so I just typed “Turkish breakfast” into a search engine, and there it was. It’s amazing what information you can find online, and even little details—like what a character has for breakfast—can add realism and flavor to a book. That’s why you need research: it puts meat on your book’s bones.