Social Media is an effective tool to communicate with potential and existing Clients and like any tool it needs to be used appropriately.
For many Small/Medium Businesses this should be used with a clear understanding of the expected outcome and that is to stay in touch with your client base and not bash them with promotions and sales material. provide genuine information that would be of interest to your audience. 
Case in point, a Tax Accountant wanting to go on Facebook and build up a fan base… well let’s face it accounting is boring as watching grass grow – However, let’s get into some more interesting parts of accounting to build up interest, such as Tax Fraud (Gossip, we all love gossip), Money Laundering, Offshore Tax Havens and now we are getting people interested!
Remember Social Media can be used to promote your work or yourself, but nobody likes a bore 🙂