Check out WRAL Channel 5 Raleigh's Go Ask Mom feature. Sarah Lindenfield Hall recommends SP Sipal's Writer's Guide to Harry Potter.
From her site:
Harry Potter books by Susan Sipal: The Pittsboro mom is an authority on how J.K. Rowling weaved the story of Harry Potter, captivating millions around the world. For the Harry Potter fanatic, her book, "A Writer's Guide to Harry Potter," explains it all. And teachers should check out her latest, "Teaching Harry Potter to Creative Writers."