Included in the questions I asked and answers I got was:
You do a lot of your research for your books through personal connections, having people who are similar to your characters in religion and worldview give guidance on scenes. How do you find these individuals, and how do you usually work with them?
I’ve found most through friends of friends, and some of them have become friends in turn — like Kier Salmon out West, for example, who has been a consultant on the Old Religion and a good deal else (she’s a translator with a lot of medical knowledge). Steve Brady in England is a naturalist, a Morris dancer, and very good at British dialects.Head on over to Black Gate to see the rest!
Using first readers like that helps you avoid what I call false-knowledge errors. As the saying goes, it ain’t what you don’t know that’ll get you, it’s what you think you know that just ain’t so.
Here's link to my favorite of his books.