Create an engaging conversation on Twitter with other Twitterers and they'll follow. Be an expert and consult or give some advice to people who needs them and they'll follow. Give something away and they'll follow.
There's plenty of other ways to do it with hardwork.
Be yourself, and be interactive. Be social. Use twitter, promote twitter, and people will start following. It takes a good bit of time, but once you have a small following, it will increase if you keep putting out quality stuff.