Writing a synopsis is one of those necessities in one's career that gets little to no attention in writing classes. This is ironic because I think it's harder to write a decent synopsis than it is to write a novel. That's because you're basically taking your entire plot, and all your character's motivations, and trying to express them on a single sheet of paper. What's worse, unlike an outline that simply gives a play by play meant to guide the writer, a synopsis has to make the novel sound exciting, fascinating, stupendous even. This is because almost always, a synopsis is a sales tool.
There are a few basic types of scenario that require a synopsis of your novel, and they are:
1. Your agent has requested one to include in a sales packet. S/he might be planning on selling the foreign rites to your novel, for example, and needs a simple sheet to hand to editors so they can judge quickly whether they want to take a look at your book. This is usually a synopsis of a book you have already written.
2. You might have written the first book in a series, and your agent will request a synopsis for the next book that she can show to interested editors. This is a synopsis of a book you have yet to write.
3. You might have been offered work for hire through a packager or a publishing house that wants a book on a particular topic. A synopsis and writing sample may be enough to land you a contract for a novel you have not yet written.
Caveat: You should never include a synopsis of a novel with a traditional submission of a book you've already written. Allow the editor or agent to read the story in a natural way so that they can judge whether it will have market appeal. They don't want to know the whole story ahead of time anymore than a regular reader does.
So what makes a synopsis good? I've tried writing them several ways, and the only way that works for me is to sit down and write it in narrative form. I just tell the story as succinctly as I can. Once I'm satisfied that I've made it as exciting as possible, I break it into short paragraphs. I arrange the paragraphs into turning points. Every time a character or the story takes a turn, that's a new paragraph. (As I write the book, I expect I'll find that these paragraphs work themselves out to be the chapters of my novel.) Once I've done this, I look for extra words, or bits of description or action that I don't need. I think the enemy of a good synopsis is too much detail. You don't want to bog the editor down as they read, and you definitely don't want your editor to begin editing the story before you've even written it. So keep your synopsis to broad strokes, and your options are more likely to remain open as you write the book. As far as length, I always try to fit the entire synopsis on a single sheet of paper. This isn't absolutely necessary, but I think having this limitation helps you avoid bogging it down with too much detail.
A final and sensible step is to have someone read it for you before it is submitted. Edit accordingly!
Anyone out there have other tips for writing a good synopsis? Please share them in the comments!