In social media trying to hard sell your goods or services is seen by most as the equivalent of spam, in fact I'd be willing to bet most would call it spamming. The fact of the matter is most people you encounter on social networks will not be directly interested in whatever it is you have to sell, and trying shove it down their throats is a good way to lose friends and alienate people.
The best way to promote your business is to be an information resource, start-up a dialog with individuals and groups, take a genuine interest in what they do and say, and then provide information about what it is you when you are given a chance. Give people enough information to follow-up with you if they are genuinely interested, it's not in your best interest to waste time trying to sway someone into something they are less than enthused about, because even if you succeed it makes the prospect of repeat business or recommendations very unlikely when someone feels they've been duped, it could even have an adverse effect on your networking efforts.
You may say what's the point of this social media stuff if I don't pitch directly to all of these potential leads I'm meeting? The point of social media is not to try to hard sell the people you meet on-line. The point of social media is to help build solid networking connections, maintain those connections, and establish yourself as an authority within your networking circles. Follow these simple guidelines and you will see increased sales.
How do I establish myself as an authority? Take part in discussions with others in your area of expertise, and supply information to those looking for it. Most social networking sites have groups centered around topics, and if there happens to be none for your area of interest you can always start-up your own, and the beauty of Twitter is that you can use #hashtags to easily find topics of interest on the site.
So what good does all this do me if it doesn't transfer into direct leads? The answer to that question is indirect leads. Establishing yourself as an authority inside of your networking circles is probably the best advertising -- and it is advertising that money can't buy. When you are able to establish yourself as an authority your name becomes synonymous with your specialty in the minds of those who view you as such, some prime examples are fast food and McDonald's, music players and iPod, or search and Google. So while your 300 Facebook friends or 700 Twitter friends may not be directly interested in your business for themselves, if you've established a good connection or have made a positive impact with them you could very likely become the someone in "I know someone who does that" the next time a person inquires them about your specialty.