7 Reasons You Should Not Use Social Media Marketing

"You are looking for a short-term answer. I have helped countless authors launch their social media platforms, only to have them call me a month later to announce that it is not "working" for them. Tweeting about your new book on Twitter is not going to mean thousands of people are going to instantly purchase it. Social media is an ongoing commitment—for the rest of your life (as an author, at least).  [...]"

http://blog.marketingtipsforauthors.com/2011/06/7-reasons-you-should-not-use-social.html