If you are thinking of using Social Media tools to reach out to an audience, the first steps are to determine your goals and your audience. Who are you trying to reach? What action would you like them to take? Once you determine your outreach/communication goals, consider the various social media tools to decide which one (or more) will help you reach those goals.
Just remember most importantly that a social media presence is more about giving than receiving. You want to make information available and provide benefit to those who choose to follow, friend or become a fan. If you provide value and information your ability to influence and get people to act will grow with your visibility.
As you build your Social Media audience I have three stages with which I measure… #1 is Audience growth, #2 is Reactivity… getting them to take an action, and #3 Stickiness… keeping them coming back and engaged.