There is a classic business metaphor that associates being in business with walking down a hallway with lots of doors. Just walking down the hallway (the state of conducting some kind of business) will reveal opportunities that you could not see until you walked down the hall. In other words, moving forward with some kind of business plan will cause you to meet people and come upon situations that may change the course of your business. That is fine, however, because it means that you are recognizing opportunities that you would not have seen if you had not taken action.
The concept of using social media to promote your business falls very nicely in line with this idea. Sites like Facebook and Twitter will allow you to make a social (sort-of) connection with many people you would not have otherwise known. And that is where opportunities come from. The more involved you are with these sites, the better your chance of using them as a tool for opportunity creation.
However, your chance of creating opportunity is better if you focus your friend/follower generating activities on those with some type of connection to your industry for geographic market. For instance, a bankruptcy lawyer in Memphis would be well served to follow and be followed by residents and business owners in Memphis. When one of those people needs help with a bankruptcy issue, they will know who to contact.
It is also necessary to keep your eyes open. If you operate your account in such a way as to get as many friends or followers as you can but you never read what those people have to say, you will not be aware when the possibility arrives to offer assistance or propose business alliances. If the number of people you follow is small, then you might be fine just using the default twitter interface. However, as your accounts grow, it can quickly become difficult to keep up with what is going on. Therefore, it is highly advisable to use a software solution to help you manage your social media accounts.
There are several on the market, and I have spent time finding a solution that works well for me. It would be a good idea for you to do the same. The one I like the best is TweetLater (http://trytweetlater.com), which automates many functions of managing a Twitter campaign, such as posting tweets, sending direct messages, and searching for new relevant users to follow. A good application for just keeping up with what people are saying is TweetDeck (http://tweetdeck.com), which lets you view your Facebook friend updates and Twitter follower updates in the same interface.