I'm just getting into Twitter for my business, and finding that as I give so I do receive. Depending on your vision will determine how scalable this model is - I'm shooting for 100 followers this week and 1000 by July 1st, and not all of this will be doable at that scale.
1) Sent the first few tweets that explained who I and the company are.
2)I followed x number of people who looked interesting and relevant to my business. Many of them followed back (very few auto-followed)
3) I installed TweetDeck to sit in the background when I'm online (and not in do not disturb mode) - there are often questions or observations from someone I follow that I can contribute to. I reply, and so far, most times I do they tweet a thank you, and I get 2-3 signups within 10 mins from their followers.
4) When I get a new follower, I have a quick look at who they follow or who follows them, for new leads to repeat Step 2.
5) Next step is to Direct message all new followers. In your case, that might be linking to your Facebook page?
A note on Facebook pages - it takes me four clicks after I log in to access my own fan page. The likelihood of me doing that for any other business? Nil.