For fiction, you don't have to worry much about how to market your book to the reading public. Once you've identified the genre and length of your work, marketing is the publisher's responsibility. Your job in fiction is to write your best possible story and target agents and editors who are likely to be interested in your manuscript. After your book is published, you'll focus on what you can do to help promote the book, such as readings and book signings, and maybe even appearances on the public speaking circuit.

For nonfiction, though, you can improve your chances of getting a “yes” from an agent or editor if you show that you know where your readers are. Take that book on herb gardens, for example: If it's aimed at people who don't have space for a traditional garden, your readers most likely live in apartments, and the highest concentration of apartment-dwellers is in major cities. In this case, then, it may make more sense to send a review copy of your book to the gardening or food editor at the San Francisco Chronicle than to rural newspapers. That's the kind of thing you would point out in the promotion section of your proposal.

It's also helpful to know where readers buy their books. This varies from genre to genre. For example, online booksellers like Amazon.com and Barnes & Noble's Web site account for about 8 percent of all book purchases. But only 1 percent of all children's books are sold online; more than 25 percent of children's books are sold through book fairs, clubs, and mail-order catalogs. On the other hand, most adult trade paperbacks are sold through traditional bricks-and-mortar booksellers, whether large chains or independents.

Agents and editors want to know that you've given some thought to creative and innovative ways to reach the potential readers you've identified. For nearly every new title, the publisher will send a review copy and press release to major newspapers and possibly magazines, but very few of those books ever will be the subject of a review. Particularly for nonfiction, agents and editors will want to know about other possible marketing venues for your book.

Thinking beyond the bookstore can help you zero in on your audience. If you're the manager of a popular day spa, for example, and your book is about relaxation and stress-reduction, you could tap into the spa's customer base for potential book sales. An agent or editor will take notice if 200,000 people visit your spa every year, and 10,000 of those have signed up for your spa's mailing list.

Book Clubs

There are dozens of book clubs that promote titles to their members, usually via direct-mail catalogs. Some of these are general-interest, with an eclectic mix of fiction and nonfiction titles. Some are highly specialized, targeting readers of romance, mystery and suspense, science fiction and fantasy, even military and history categories. If your book would fit well into a book club's title list, mention that in your cover letter or proposal.

Associations and Organizations

Social and professional organizations are fertile ground for finding readers who already have an interest in your book's topic. Your high fantasy novel, for instance, probably would appeal to Renaissance re-enactors, and there are several such organizations around the country; you might even be able to sell your book at some of the countless Renaissance fairs. Veterans groups would make a sensible target for your memoir of Pacific Theater military operations during World War II. Your herb gardening book might hold special appeal for members of gourmet cooking clubs.

Many of these groups have newsletters for their members, and these newsletters might accept advertising or reviews of your book. Some even have mailing lists, which you or the publisher might be able to use for a direct-mail or e-mail promotion.

Specialty Publications

Don't overlook magazines in your market research. While it can be incredibly difficult to get your book noticed by national magazines, the possibility still is there, and you should take this into consideration. At the very least, circulation figures can help bolster your argument that there's a market for your book. Bon Appetit has a circulation of well over 1 million — an impressive market to reach with word about your herb gardening book, and a tempting target for a publisher.

Market directories like Writer's Market include vital statistics on a broad range of magazines, often including a profile of the magazine's readership. This should be a core part of your research. You can use this information to further refine your book idea and zero in on your target audience.

Keep in mind that your research is mainly designed to show a potential agent or editor that there is a strong available market for your book. Most of your ideas for promoting your book will never be implemented, for a variety of reasons, but that shouldn't concern you. As long as you can demonstrate that you have studied the market and thought seriously about whom and where your readers are, you'll have an edge over the innumerable wannabe writers who don't do their homework.