A couple of years ago, Steve Harrison, who runs www.howtogetaliteraryagent.com, hosted a panel of four agents including Jeff Herman (pictured). Herman said he wants the answers to two questions when he gets a query letter:
1. "Why, given all the choices that everybody has for their information [and] entertainment today, is somebody going to spend $25 on your book?"
2. "What about you and what you're doing, as far as your activities, that's really going to help support that book in the marketplace?"
If he likes your answers to those two questions he'll ask for a book proposal.
It's a good idea to have those two questions in mind right at the start and let them guide you during the writing process. For example, for question 2, you might want to set up a blog that relates to your topic and build up a following during the time you're writing the book.
(For lots more practical tips on how to write and promote a book and get an agent, see my book, "Your Writing Coach," published by Nicholas Brealey and available from Amazon.com and other online and offline retailers. And if writing screenplays is your thing, check out my new site, www.ScreenWritingSuccess.com.)