So you have a scintillating concept for a book, you've penned a tight, persuasive proposal (click here  to learn how), and now you need someone to sell it. Realize that a typical acquisitions editor at a major publisher reads dozens of proposals every week with only a scant 1% ever seeing the light of printed day. It's a cold, cruel world out there, and even established writers with a track record in selling books can have trouble cracking the code. Enter the literary agent, who acts as an author's Consigliere, business partner, chief negotiator, and bodyguard during the publication process, when the best intentions can suddenly go awry.
Forget about approaching publishers without one. Virtually no editor at a major publishing house will talk to you about your project unless it's submitted through standard agency channels. Years ago editors may have nurtured young talent and sifted through slush piles in search of the next great writer and book, but nowadays they mostly acquire new projects and shepherd them through the publication process. Many barely break out a red pencil to edit. Agents have assumed many if not most of these roles.
But a good literary representative does far more. She (or he, naturally) discovers new talent, offers editorial guidance and polishes your work, and maintains ongoing relationships with editors so before your proposal ends up on their desks they are excited about reading it. If one or more publishing houses comes to the table she negotiates the deal, including the advance, royalty rates, and what rights you keep (Hold on to multimedia rights. They may be worth something someday.) Will you be paid in three installments (on signing, upon handing in a publishable manuscript, and when the book officially comes out) or four (when a paperback comes out--if a paperback comes out). She'll push for marketing, which sadly for most of us won't amount to much. She acts as a liaison between you and your publisher before, during, and after your book is published. Because what if your publisher wants to change the title or designs a cover you hate? Your agent plays bad cop while you can stay above the fray. Her take: Usually 15% of whatever you make.
This is all well and fine, of course, but how do you actually find one? Assuming you have a saleable idea, one tried and true strategy is to trek to a bookstore and leaf through the acknowledgements of titles on a similar topic as yours. It's de rigueur for an author to thank his wife, kids, first readers, friends, dog, cat, hamster, editor and agent, not necessarily in that order. There's also a Web site, agentquery.com , which lists agents by the types of books they represent, and the Literary Marketplace , available at many public libraries, is also handy. Perhaps the best way to find an agent is also the simplest: word-of-mouth, which comes with a built-in bonus--a personal introduction. So if you know any authors who have published books that touch on themes you wish to explore, request a favor.
Don't just send your proposal to an agent without asking first. That's considered bad form. Try to find out what mode of communication the agent prefers on initial contact--you might find it on her agency Web site, through the agentquery.com database or in the Literary Marketplace. In my case, I usually send an email with a brief description of the book and a short bio asking permission to send a completed proposal. The proposal is key. It's virtually impossible to divine how an idea will be executed on the page without seeing something written. Writing hard news is different from penning magazine features, and publishing books is a completely separate art form from magazines. Screenplays and theatrical productions require wholly different structures and narrative techniques. Respect these differences. Just because you've mastered one form doesn't mean you know what the hell you are doing in another.
Ask a literary agent what the biggest turnoffs are and she'll tell you a poorly written query letter will almost assure you a rejection, as will providing too much or too little information in your introductory note (a simple link to a blog post, for example, is less than useless). Make sure you've researched the marketplace, because even if you can't name other books that cover similar terrain, she can. Never approach two agents at the same agency at the same time, which would be a bit like asking two roommates out on a date. Be sure the material you want to write about is appropriate to this particular agent, since they usually specialize. You wouldn't hire a chiropractor for a bad heart and you wouldn't hire an agent who specializes in children's books to represent a work on the sex lives of dung beetles. That doesn't mean a good agent can't sell a really good proposal with commercial potential in any genre. But they specialize for a reason--usually based on intrinsic interests.
What do they look for? It's obvious: fantastic writing, an engaging voice, intriguing ideas, a platform from which to market the work, and a work that will likely result in a sale. But even top agents can't sell the unsellable, nor are they miracle workers who can magically gin up six-figure advances. That's up to you. Or rather, it's up to your book proposal.
Adam L. Penenberg is author of Viral Loop: From Facebook to Twitter, How Today's Smartest Businesses Grow Themselves . A journalism professor at the Arthur L. Carter Journalism Institute at New York University, Penenberg is a contributing writer to Fast Company.