How many times have you seen a link to a personal website or online portfolio in someone’s email signature? It is rare. You receive a message, maybe an attachment, and some boring, insincere signature. Contrast that with receiving message on facebook or LinkedIn where a picture is displayed AND the name is linked to a personal profile! Wow. That is a world of difference. Now, I can find out everything about that person if I choose to. Knowledge is power, and it is helpful to be armed with information when reaching out to a client, customer, or prospect. For example, you can compliment a prospect on a recent blog post, or scan their profile for something in common. Now you have something to talk about and it is a nice transition into conversation.
I would strongly suggest changing tone, sentence structure, and even word choice to be more personal when using social media to communicate. Maintain a level of professionalism but do not structure every message like an email. Follow the flow and pick up on the style of communication of the other person. It only takes a couple messages before someone reveals their typical style of writing.
In the end would you rather buy a glockenspiel from a friend or from a stranger? Well then if you are trying to sell something, go make friends!