Richard Bach once said that a professional writer is an amateur who didn't quit. Many would-be writers cap their pens after receiving a single rejection slip. Some writers set timelines or submission quotas to meet; they give themselves a year to market their book, for instance, or they decide to send their proposal to twenty-five agents or editors. If they reach the end of the year or the twenty-fifth agent without scoring an acceptance, at least they know they've given their work a fair shot.

These kinds of goals also are useful in motivating you to re-evaluate your book idea. If you're getting constructive criticism with your rejections, you can pool the notes from agents and editors to see if a pattern emerges, and you can decide whether it's worthwhile to continue with your original work or whether it's time for a rewrite. Alternatively, you can decide to give yourself a rest from this particular project and file it in a drawer until you're ready to retool it or start a new round of marketing.

Sometimes the timing just isn't right for a particular book idea, but that doesn't mean the right time won't come around. Jonathan Livingston Seagull was rejected more than a dozen times before it found a publisher. Ironically, the publisher that eventually picked it up had rejected the manuscript a year earlier.

If you get significant feedback from a specific agent or editor and decide to take the advice offered, it's a good idea to resubmit your proposal to that agent or editor. There are two good reasons for this. One is that you already know the agent or editor is interested, so you start with that advantage. The other is professional courtesy. An agent or editor who gives you his expert advice at no charge deserves the first chance to look at how you applied his advice. This doesn't guarantee that you'll land a contract. But it does show the agent or editor that you appreciate his time and his comments, and that polishes your image as a professional, whether you're published yet or not.