Write your book's rationale and every part of your book proposal on the computer so that you can print it in a professional manner. If your rationale looks sloppy and amateurish, no publisher will bother to read what it has to say.
Explain your book's general premise in the first paragraph. This is the paragraph in which you describe your book's purpose.
Describe the ways in which you are the right author to write this book. Explain what qualifies you to share this information and how you are able to connect with your book's audience.
Detail your book's benefits and features in the next paragraph. Be clear about what your readers will be able to do after reading your book.
List the marketing activities that you are willing to do to promote your book. This includes speaking engagements, talk shows, classes and book signings to promote your work.