There are several different aspects that play into determining the best social strategy for a brand. As I mentioned in Mobile Friendly Messaging, the brand needs to identify how their existing fans/followers were acquired, what the customers expect of the brand, and how to turn their social media pages into destinations for their customers.
These, and many more, are the questions I ask brands to answer prior to setting a clear strategy for the social channels. If a brand puts out a strategy that wasn’t thought through till the end, then it may push some of their existing fan/follower base away to never return. With a clear strategy and goals in mind, any brand can make social media a success, you just have to find where you fit with your customers to make them need you to be there for them.