To get more followers on twitter (I have 5300+ now), there are three main ways of gaining followers:

1) Proactive means

2) Passive ways

3) automated following

All of these methods rely on you putting up interesting content to your target market. Plus following the rule of thirds for your tweets – 1 third about you and what you are doing with your business (not selling, just talking about what you are getting up to in your business), 1/3 replies to people – after all you are looking to engage with your followers, and 1/3 about your business, e.g. blog posts. Until you are established on twitter (think 500+ followers), don’t be tempted to advertise on twitter. Out of about 10-15 tweets I post up a day, I only allow myself 1 tweet which is an advertisement for one of my products.