Be genuine, straightforward, and a positive force of good. You can't change the past, but you can reassure consumers that things will be different in the future. Just make sure that it's not just lip service -- that things actually change.
Be a human. People react better to a human face with a real name than they do to a "spokesperson" making a "statement," or even a "social media manager" responding to comments. Bring the product manager, the CEO, or some other leader out to respond to complaints in their own authentic voice.
Let power users emerge. Don't try to respond to everything as fast as possible. Leave room for power users to emerge by providing clear information and then empowering users to defend the brand and share the information, rather than trying to address every single Facebook comment and tweet as it comes in. You'll probably find that, in the end, you've created an even stronger community than you had before.
Redirect the conversation. Your Facebook page is a one-stop shop that acts as a brand hub, meaning that anyone who visits it might be confronted with negative or accusatory messages about your brand during a crisis. It often makes sense to redirect that conversation to venues that are less centralized and public -- and where the shelf life for comments is much shorter such as Twitter (online) or a call center (offline).
Don't shoot from the hip
So your company finds itself in the middle of a social media crisis. The last thing you should do is haphazardly respond to the issue without getting all the facts. How does one go about this? Listen, listen, listen! Find out what consumers are saying about the issue on Twitter, Facebook, and other outlets. Tools like Google Alerts can be an invaluable resource for this as it can help you keep track of what consumers have to say about your company. The key to this step, as LeWinter said, is speed as "silence can often be as bad as a misguided response." Once you have a better understanding of how consumers are reacting to the crisis, you can proceed with the next steps to suppress the fire.
Don't deny the facts
Any attempt to skirt away or deny the issues at hand will inevitably fail. With today's saturation of social media in the consumer population, the issue can hit Facebook or Twitter in a miniscule amount of time, exposing itself to millions. Nobody wants to hear excuses and even fewer people want to hear silence regarding the matter. The best method to confront the issue is to be up front with the public. Dominos is a shining example of this with its acceptance of the widespread dissatisfaction with its product. The company opened several social media outlets as avenues for dialogue with its customers to find ways to improve its pizzas.
Burger King got to exercise along the lines of this point on Presidents Day, as its Twitter Account was hacked and jokers uploaded a McDonald's logo and plenty of anti-BK Tweets. Since the people managing the Twitter Feed for Burger King were able to alert Twitter within an hour, the account was hijacked for only 75 minutes and down only until the evening. The whole thing was over in a half-day, except the news reports that seemed to humanize it in Burger King's favor. Even McDonalds seemed to feel BK's pain, as the Chicago Tribune reported. "We empathize with our @BurgerKing counterparts," rep for McDonald's said via the actual @McDonalds account. "Rest assured, we had nothing to do with the hacking." That makes one wonder why the rep wrote "empathize" and not "sympathize." But I digress.