One of the current trends is the use of social media to promote books and build an author platform. To say the advice "out there" is a bit overwhelming and confusing is a bit of an understatement. I have far too much to do to spend hours and hours on Twitter, Facebook, etc, unless it is going to be a productive use of my time.
I stumbled on a source of information on this topic that was helpful and can be found on Joel Friedlander's blog for self-publishers. The article is a guest post by Steven Lewis and is titled The Five Best Tools for Promoting Your Book on Twitter.