When I revised and reprinted my 360-page comprehensive local history book, I sold almost enough books through my personal mailing list to pay the printing bill. That book also sells consistently through local bookstores. While I sold very few copies of my mainland luau book through my mailing list, I had tremendous response through book reviews in cooking magazines and press releases to newspapers. In fact, that book is in its third printing and was recently picked up by a traditional publisher in Hawaii. One of my favorite methods of selling books is through magazine articles.
Articles provide much greater exposure to a larger audience than most ads.
When you write a book, you become an expert in that topic. Of course, it's okay to mention your book in an article if it's presented in an informational way and doesn't appear to be a blatant commercial attempt. If your book is a study of travel maladies, for example, and your article features how to avoid motion sickness, jet lag or a weather-related ailment. There's probably little need to mention your book in the body of the article. Let's say I'm writing an article based on people I know.