In order to sell a work of non-fiction (i.e. a memoir, biography, travelogue, How-To book), you must write a book proposal. It helps to think of it more as a "business plan" than a literary creation. The goal of this document is to convince a publisher that this book will sell lots of copies. Book proposals are very long and involved documents. (My proposal for Around the Bloc was over 100 pages!)

Book proposals consist of the following parts:

A. Overview
A one to four page description of the project.

B. Approach
A paragraph that includes the number of sections, chapters, and pages to be included in the book, along with any "Front Matter" or "Back Matter," such as photos, maps, glossary, bibliography, index, etc.

C. Competition Analysis
A brief "book report" on works similar to yours, along with why yours will be better.

D. Market Analysis
Who exactly will buy your book? Be specific, such as "Mexican-Americans, age 16-35" along with a Census count of that population. If it's a travel book, find out how many Americans visit that country each year, how many students study its language, etc.

E. Promotion Plan
How will you find those people? Elaborate on radio, TV, Internet, and print outlets as well as bookstores, college speaking tours, etc. Read Jacqueline Deval's Publicize Your Book! for ideas. This is one of the most important sections of the proposal, and should be as detailed as possible. Pretend you have an unlimited budget and oodles of time.

F. Author Biography
No modesty here - go off.

G. Outline
Table of Contents.

H. Outline Defined
Brief description of each chapter.

I. Sample Chapter
One or two of your best chapters (not necessarily the first).

J. Accompanying Materials
Author photo, previously published clips, any articles that have been written about you or your subject matter, etc.

An excellent resource is Michael Larsen's How To Write a Book Proposal. I know at least five writers who swear by it, myself included.

Good luck!