The new book by Dan Zarella (reviewed here) has plenty of applications for authors. I highly recommend that you purchase the book, but wanted to share the top three tips from the book for authors.
1. Build Authority and Claim It. Zarella found that Twitter users with the word "author" in their username had, on average, almost 100 more followers. While this is not necessarily cause and effect, it does indicate that authors should not be afraid to identify themselves. Building your authority and claiming it will help you reach more people. Interestingly, Zarella also found that self-referencing in your posts is not helpful, so include most of your claims to authority in your bio, not posts. His advice: "Talk as yourself, not about yourself."
2. Originality and Familiarity. Zarella found that ideas that are both original and familiar are the ideas that are most easily spread. For authors, find a way to separate yourself from the genre, but don't abandon everything. Unique perspectives on common subjects can boost your book's marketing quickly. For more information on how to brand your books, I suggest picking up a copy of the classic marketing book, Positioning.
3. The When of Social Media. The author found that Facebook posts are shared more and that blog posts are commented on more often if they originate on a weekend. Don't work harder, work smarter - post during the optimal times and the same marketing will go much further.
These are just three tips from the book, there are many others that authors can apply in this 80 page manifesto. Pick up a copy and see your social media reach take off.