There are a bazillion guides to social media floating around out there.
I thought I'd round up some of the best:
Ten steps to helping your business kick ass on Twitter
19 presence management chores you could do everyday (Note to self - Presence management. I like that.)
Ten commandments of social media
Why trust is important in social media
Leveraging social media in regulated industries
Seth Godin speaks about social media
These are just a drop in the ocean, of course, but if you start with them, you'll have a good grasp on what you need to know to get started (or make your current efforts more effective).