Welcome to the forums. You are asking a HUGE question with no quick and easy answers. It's something like "how do you do marketing".
There are a few guidelines for any business getting into Facebook and other social media venues, and I'd say the first is plan to be involved - humanly involved, not just involved via automation. That means you must have time and human resources to invest.
I would suggest you do a search for pubcon which had a couple very good presentations on this theme. Several independent bloggers covered pubcon and you can find good coverage of insights given by speakers - which unfortunately do not appear to be available here - even in the supporters area.