Research competing titles. Search bookstores, libraries and the Internet for books that relate to your subject. For example, if you have written about General Ulysses S. Grant, then competing titles would include nonfiction books about the Civil War or General Robert E. Lee. Find books published as recently as possible. This will show your agent or editor that there is a demand for your title now. Make a list of three or four competing titles that you consider to be the best and most prominent in your field. Include title, author, publisher and publication date. Next to each book, jot down what it tries to do. The competing title might try to give an in-depth portrait of a historical figure or attempt to create a narrative out of a famous scandal.
Establish your niche in the marketplace. On your list, write down some notes on how your book differs from each competing title. You have proved that your general field is of interest, now you have to show that you are contributing something different to the subject area. Show how your perspective differs from the other competing titles. You might be focusing more on the personal relationships of a historical figure as opposed to his place in history, or you might be giving more comprehensive details of a historical event than ever done before. Convey what you are sharing with your audience that has not been shared before, especially if there are very few competing titles in your area.
Write the section. Give the title (in caps), author, publisher, and publication date of a competing title, i.e. A STUDY OF JELL-O by Clementine Gelatin (Jiggly Publications 2009). Briefly, in one to three sentences, describe what the title accomplishes. Then write one to three sentences explaining how your book differs from that title. Repeat this for each of the competing titles. Revise the section, checking spelling and grammar.