1. Hire the right person for the job. Too often, companies hire technologists (or worse, administrative staff) to handle the communications function. Hire a writer--the best writer you can find. Anyone can learn how to use technology, but not everyone can learn to write at high-quality levels.
2. Allow that person to do his or her job. Nowadays, it's about being able to respond, to enlighten, to educate in an instant...not to bring to a corporate discussion of "Should we do this or not?" that takes days, weeks or even months (gasp!) to decide. Social media is in real time and so should the company's efforts be. Large companies are no exception to this rule--they need to lose the layers of authority and let the communicator...you know...communicate. If you don't have the trust to allow that person to do his/her job, then you've either hired the wrong person or you still have the wrong mindset.
3. Make sure that all you do is part of your large content strategy. Again, hire the right person, let him/her do the job and make sure that that person has all he/she needs to incorporate the fast-moving social media efforts into the bigger content picture. For example, if responding to a real-time social media event, analyze if this topic/event part of a trend? How can that trend be expanded and used in the company's content strategy? You can't just post on Facebook or Twitter, etc., and forget to follow up. It's all about seeing the big picture simultaneously with the little picture--which takes an expert eye and a whole lot of talent to do in the first place and to implement in the second.
Hire the best, get the best!