The following advice from Maya Angelou applies not only to marketing books but also to writing books, publishing books, self-publishing books, producing ebooks, pursuing publicity, and just about everything else you do as a book author and/or self-publisher.
Pursue the things you love doing, and then do them so well that people can’t take their eyes off you. — Maya Angelou, poet, memoirist, and civil rights activist
Note how this applies to you when publishing and marketing your books. Create books so good that people just want to be around you, want to see everything you do, want to share everything you do, and want to always be a part of your tribe (or fan club). — John Kremer