Your signature should include your name or pen name, your current website or blog, and the title of your book with an easy buy link. You can attach a graphic of your book cover if you wish but many
email providers do not show images for fear they may be infected with malicious code.
Standard Signature Delimiter
One problem with signatures is that they repeat at the bottom of every message. So if you have an extended email correspondence, your signature could be repeated three or four times at the end of
the whole sequence rather than at the end of your most recent message.
Try using what is known as the standard signature delimiter. This consists of typing two hyphens and a blank white space on a new line before your signature like this:
author and editor
photo by Marcolm, image by digitalart, both thanks to Free Digital Photos.
And find another great post on signatures here, posted by A Tarkabarka Hölgy for the A-Z Challenge.