According to a few books I have read on the subject of increasing book exposure and sales including in the book "The Step - By Step Guide to Self-Publishing for Profit" by C. Pinheiro , a great technique is to get book reviews. It can even be more cost efficient than paid advertisement. Especially if you are marketing your books / books with Amazon.com there is allot of support for book reviews and reviewers. I myself place a review on every book I read with Amazon.com. As I just published a new book I would suggest an exchange where authors in similar genre's or interest, trade books , read them , and review them. Already, I have started this with some of the members of CAPA and it is working out just fine.