If you are going to get the most value out of using social media, it is important to remember what is at the core of social media - building more trust and stronger relationships. If you think about it, how many relationships have you personally built by not engaging in a dialog but by dominating the conversation. Social Media isn't any different, if you spend your time "TELLING" instead of "HELPING" you will end up with the same result as you would with any other relationship - it won't happen.
Social Media is designed for engagement, interaction, and helping others along the way get what they need to do better in their business. It is tough to help others when your time is spent promoting and pushing your agenda. When in doubt, just ask yourself what part of the term "promotional campaign" is linked to helping and building trust in the relationship. None. Where marketing and traditional marketers get hung up is when the primary words in your vocabulary are "promotional campaign" it is hard to focus on the words "helping" and "trust".
Social media gives individuals and organizations the leverage to help others and in the process build trust and relationships with you because you are helping them be successful. The audience today doesn't want more stuff and noise pushed at them, they have learned to be very particular about the information they receive, because they can. If you change your focus from the "telling" aspects to the "helping aspects, you will be amazed at the value others receive. From this they will not only want to follow and engage in what you are doing, but spread it to their networks of friends and colleagues.
This is what helps you get to zero cost marketing because your network is doing it for you. By you helping them to be successful, they in turn are helping you be successful by sharing your information and stories to others you may never have reached otherwise. That is the power of leveraging social media.