The people that buy a book about how to do something are not interested in having you tell them how wonderfully you do something or how wildly successful you are at doing it, they are expecting you to tell them how to do it, and not in a condescending manner. If you convey an image of superiority and write to them as if they are stupid, you are going to lose many readers fast.

When you write your book and when you write things to promote it, step back and think about how you are coming across to the reader. You can capture their attention with a conversational tone to your writing and give them examples of your personal experiences, but do not make your experiences sound like boasting. Your reader bought your book because they felt you were credible and know the subject. You do not have to fill the book with things that do nothing but annoy the reader, in fact, avoid writing anything that could be construed as self-promoting unless your book is supposed to be a "How Wonderful I Am And Why Everyone Should Adore Me," type of biography.

Much of this applies to promotion as well. I have seen all kinds of promotional pages all over the web and I am sure you have too. Do you get as tired of the hype as I do? When I read someone's marketing page, I really do not care how successful they have been at doing whatever it is they are marketing, I want to know what it can do for me and I do not what it blown out of proportion. I want to know what the realistic expectations are, what it requires of me, what tools are available for me to use to draw my own conclusions, and some credible independent reviews by others that have tried the product. If the promotional materials are hyped, then I expect the entire book to be hyped as well. If the marketing materials present things to me as if I am an idiot, then I would expect the same treatment from the book, and I do not really want to pay for anything that treats me like an idiot, do you?