When marketing a book, try to keep all of your author produced material to a general theme concerning format.  This might include choosing a paper/card stock color, keeping the major amount of your fonts the same (many even make sure it matches the book).  You may even choose a “theme” (ready made design – often involving graphics)  from a publishing program and carry it throughout.  Like any large retailer, this “small stuff” will help build what is called Name Brand Recognition.  When they see the envelope in the mail, they know without even looking it’s from you.  If they see a flyer they know it’s about the book without reading it.  Many “repeat authors” even carry the design over to other projects.  Some keep the exact same design format, others change one or two elements such as color or headline font.