I found it hard at first to think of what I would want to say to the masses because I am not typically in the habit of shouting my opinion to others.  I had to change that frame of mind in two ways:  First, I realized I am not shouting because these people have chosen to listen (follow) me.  Second, I have opinions, and sharing them shows people where I stand on a subject and gives me credibility.  I believe that posting should be positive in general.  I subscribe to the old rule “if you don’t have anything nice to say…don’t say it” with one notable exception.  I am looking for help from a company and I am genuinely interested in opening a discussion to resolve the problem, I might express that in my posting while still not making it negative or nasty.  This gives the company the chance to shine or stink based on their own replies, and often the masses can contribute suggestions too.  When you are posting, consider asking thought provoking questions, and look for ways to engage your audience.  It is a great start to get people to read, but ultimately you want them to feel engaged in the collective discussion.