Write a press release and send it to local newspapers and television and radio stations that focus on local news, arts or events. Introduce yourself and give a brief description of your book. If your local newspaper has a dedicated book reviews section, address your press release directly to that section's editor.
Contact bookstores and libraries in your area and ask if they will stock your book and let you hold a reading and signing event. Be aware that many larger bookstores have policies against stocking self-published books, while smaller independent stores are often more open to it. Be polite and professional when you call, and don't be discouraged if your request gets denied.
If you're successful, help promote the event and let people know your book is available there. The more people who turn up at the reading and the more copies sold, the more likely the bookstore managers will say "yes" the next time you bring them a title.
If your book is fiction or poetry, contact local coffeeshops and ask if you can hold a reading there. Many have open mic nights already established at which you can sign up to read excerpts from your work.
For nonfiction books, look for a local club or organization with a purpose that matches your topic. If your book is about local history, for example, contact local museums and historical societies and ask about giving a presentation at their next event.
Participate in web forums and communities pertinent to your book's subject. Find your book's "niche market" --- whether it's science fiction, gardening or coin collecting --- and become active in related online communities. Be aware that many online communities, especially the larger ones like Reddit and Digg, have policies designating most kinds of self promotion as "spam," so check the community's posting guidelines or FAQ to make sure such posts are welcome. There are also a number of active forums dedicated to self publishing, some of which are listed in the Resources below.
The Google Books Partner Program (see Resources) is a free program that allows authors to promote their books. After uploading the book as a PDF file, the book will be indexed by Google and made available to user searches, helping match your book's content to the audience who is looking for it. The program allows you to link back to a website or online store where users can buy the book. It also gives you complete control over how much of the book is made available for preview, protecting your copyrighted material.
Perhaps the easiest but also one of the most effective methods of promoting your book is through social media and social networking sites such as Facebook, Myspace and Twitter. Through these you can promote your book through your own profile, make a fan page or group, post excerpts, and update fans with information on readings, events or developments on new work. If you have access to audio or video recording, you could make a video "book trailer," or make a recording of yourself reading excerpts available as an audio download.
Warning: Be sure to check the site's license agreement. Some social media sites consider anything posted on their site automatically under their copyright, which could prove legally complicating down the road. You could still use these sites to promote your book, but you just wouldn't want to post excerpts there.