It's fantastic that interest in social media is so high, but I'm alarmed at the number of brands and agencies that are ready to jump into social media to take "advantage" of audience concentration in Facebook, Twitter, and other fast-growth outposts. What's lacking in most social media programs is an actual strategy.
If you don't know precisely why you're in social media, with whom you want to engage, and how you're going to measure success, you're not ready to start.
I use a 7-step Social Media Strategy Worksheet to create a framework that governs what the initiative aims to accomplish. (You can download the Social Media Strategy Workshop as a PDF here, and use it as much as you like, with attribution).
Step One: Describe the Business
Sounds basic, but if you can't describe the precise value proposition of the brand in a sentence (without a bunch of mission statement crap-ola), you need to figure that out first.