The first step that needs to be taken is to create a social media management team that will help in developing a well rounded policy that will work for everyone. This will also help you develop steps in case of a crisis regarding your brand that needs to be averted in time. Once you have a team in place you can decide who handles what kind of issues.
When it comes to social media it should be more than just an exercise; it should be a culture! When you create a policy for your social activities try to ensure that you learn from it and implement changes as you go along.
Make sure you do not have a generic policy that applies to all sites. While it is important to create an overall policy, ensure that you have site specific policies that will ensure that there is a better chance of having a better social media experience.
When you create policies it is important to have two separate policies: The first one for those who want to use social media for the company and the others who want to use it for their personal work. In both cases it is important to clearly articulate what can and cannot be said about the company and what activity will be helpful to the brand.
Lastly make sure you stay updated about the dynamic nature of social media and update your policies as you move ahead.