I do book research by checking out everything the library has to offer on the subject and reading it. Then I talk to experts in the field to fill in the blanks created by reading the books. Then I set out to start my writing. My last book involved reading about 20 books on the subject and talking to four team coaches to fill in the blanks left by the football books out there. I also came up with a lot of anecdotes from the coaches which was really helpful for my subject. You just have to make sure it's ok to quote them in your book or work from your own personal experiences for anecdotes in the book.