Not all social media avenues are right for everyone.
It depends on you ideal target market, where they are gathering and why they are interested in.
I was talking to Anthony from an office supplies business and we were discussing how the best form of marketing for him is not Facebook for Twitter, but in fact email marketing first, followed by LinkedIn groups.
Email marketing for him means he can put special offers in front of his existing and prospective clients and a very targeted way. Email marketing is the way to do that.
If you have a good database set up, and prepared to write short emails with links to specials back to your website, it can be very powerful. Good tracking from your email broadcast account will also tell you which offers are creating the biggest effect and sales.