On his personal branding blog, Dan Schwable interviewed author and speaker Phil Town (picture at left), who made this observation about publishers:
“The key thing to understand about the publishing industry is that they don’t sell books, they publish them.” Since they don’t sell books, they look for authors who can sell the books if they publish them. This ability is highly prized. They will pay you a lot of money for your book if you can show them how it will be sold in large enough quantities that they’ll not only get their money back but also make a profit.”
He adds: Here’s the marketing tip of the century: create a large group of fans who will buy your book before you write your book.”
And that's where building up your presence on Facebook, or via a blog or a podcast, or Twitter, and other ways to reach people with interesting and useful or entertaining material comes in. It's harder to do for fiction, unless you are in a niche (like Civil War novels) that allows you to find likely fans.
