Chuck Sambuchino, who writes for Writer’s Digest, offers three primary reasons why manuscripts are rejected by agents:

First…the story they’re reading is in a genre or category outside of what they handle. Form rejection. The second reason they say no is because of poor writing skills: grammar, punctuation, sentence structure, etc. Form rejection. The third and most common reason that good writers get rejected is that their story just plain isn’t ready yet. In other words, it’s good—but simply being good doesn’t cut it. A piece of fiction has to be great to catch an agent’s eye.

Each of these issues has a solution.

First, research the agent before submitting. There are a host of resources out there, including the annual guides to agents and book publishers. Always go to the agent’s website to look up information about that agent. While you’re there, check out their fellow agents to see if someone else is actually a better fit. And be sure you know your manuscript’s category! Know not just the primary category but the subcategory. If it’s a true crossover (and not just a thriller with a love story embedded in the plot, for example), know which categories it targets. If you state the category in the query and it doesn’t match the sample pages, you’re going to be rejected.

The second issue is easy to fix. Work with an editor to clean up the manuscript or to do the deeper line editing some manuscripts require. Do not rely on your next door neighbor who is a college professor…professors live inside academia, and the world of academia is insular and separated from standard publishing by a thick brick wall. Do not ask your high school English teacher or a journalist to edit your memoir, business book or novel…they will utilize a more formal style that turns off agents, publishers and readers. Do work with a professional–a fellow novelist, memoir author or business book writer, a freelance editor, or someone you trust from your writer’s group.

The third challenge might require more work from you. Get feedback from authors in a writer’s group or a reader you trust. Ask for conceptual ideas. Don’t let someone get bogged down in editing your spelling errors. Ask for the good stuff: Is the plot exciting? Which milestones don’t track well? Does the suspense constantly rise? Are the characters developed well enough? Writer’s Resource offers written analyses at several price points that can help you with this step.