Since 80% of all books are sold by word-of-mouth, your primary goal in marketing your books is to create a core group of people who will spark that word-of-mouth. I like to think of these people as the officers for your word-of-mouth army, because what you ultimately want to create is an army of people talking about your book. In that army, you'll have privates, corporals, sergeants, lieutenants, majors, colonels, and generals. The moment someone meets an author, they've self-promoted themselves to at least a corporal. If they get an autograph, count them a sergeant. If they buy ten books for other people, promote them to lieutenant. You get the idea.
In my 1001 Ways to Market Your Books army, I have at least four five-star generals: Jack Canfield, Mark Victor Hansen, Bob Allen, and Dan Poynter. They've earned every star. Indeed, I have many other one-, two-, three- and four-star generals. Plus lots of captains, majors, colonels, and other uppity-ups.
Note: If you don't like the analogy of an army, then think of it as a parade, or a circus, or fan club, or a really great party. Help others to join the fun!