Co-Authors? How Successful Are Partnerships on Books--and What Are the Pitfalls to Watch Out For?

When my first book was contracted by a publisher, I was assigned an editor who also wrote for Men's Health magazine.  This editor, being a writer too, knew how scary it was to have a first book.  I knew very little about how to structure a book; my editor showed me the ropes.

Not long after that book got published, I got a call from the same editor.  Wou…