Hi Julia,
You can 'buy' likes, which makes your page look popular and so more people follow, but I never think it's worth it. At the end of the day, you want to be speaking to people who might come by and buy something.
There are loads of online tips from 'marketing experts' on how to get more likes. Supposedly as long as you keep posting good quality, relevant content that people will 'share' they should build naturally, but running competitions, having links to your profiles across your website etc help too. Giving people an incentive to like your page is a good way, or why else would they bother? Competitions etc are a great way to go, but time consuming. They also say that being personal is the way to go. Be 'Julia from Make' instead of just MAKE, but I don't do that as I feel it'll be a different set of followers, and what I want is people who are interested in my business, not me.
I've found that the facebook inbuilt advertising is pretty good for increasing likes, and I have had customers coming in as a result. as they've 'liked' my page from the adverts, then responded to posts on what I have new in stock and bought them.
With twitter, just posting interesting things and retweeting builds it up pretty well. If we all retweet each other a bit we should be able to grow the following between us. Again with twitter, you can buy followers, but I feel it;s pointless - why speak to a deaf crowd?
I think Sarah (Room 212) is heading up a bit of a Gloucester Road marketing team, and with that will get going on the social media channels already set up for Gloucester Road. If that gets sorted, it could be used to promote the social media accounts of all of the traders on Gloucester Road, tweeting about everyone's events, special offers etc. And Gloucester Road itself has a good fanbase and is renowned enough to get a good following as long as it's active enough to be worth following

Overall, I think the number of followers you have shouldn't matter as long as they're good quality followers who might respond to you and [purchase down the line.
Hope that helps a little bit! Not the most useful answer, but hopefully it'll help in some way.