Most authors I know are not rich and need to find ways to promote their books for as little money as possible.
Most people have heard of “Social Media”, but many are not clear on what it is even if they use it every day.
Essentially, Social Media is any place where people visit. This is sites like Twitter, Facebook, Blogs, Web sites, and YouTube. All of these services are free if you just look around.
Talk with other blogs or groups to hold a virtual book tour for your book.
The main point of this is that you need to let people know about the book almost before you begin writing it. Authors need to build reader interest in their book, and how it's progressing.
Writing about your book and letting people know about is the best way to build interest in the book and you as the author.
Word of mouth is still the best form of advertising. So is making friends by writing about your book and becoming a real person in the eye of the reader. The more they can relate to the author on a personal level as a writer they would like to read is to develop a relationship with readers using and sites where possible readers might congregate.
If you don’t have accounts on popular sites, consider opening one and start writing about your book on a personal level and not just harping about buying. You want to establish relationships and encourage people to become friends on these sites.