Avoid the words I, we, us, and our unless the book is about you. Editors are wary of authors who overuse the word I unless it's relevant to the book. Unless you or your experience are part of the book, write about the subject, not yourself. Also avoid the words you and your in your introduction and outline. The first two parts of the proposal are about the book. You're writing them for the editor, not the book buyer. If you want to address readers directly, as this sentence does, do it in your sample chapter and the opening anecdotes for your outline. The most effective way to sell your book is to stick to the subject and the book.