liberal use of hashtags to do with what you are talking about will help to get relevant followers such as if you are talking about a product (#iphone) or perhaps a sports team, sometimes if there are any topics that are trending and to do with your site or business it is a good idea to comment on it or link to a blog post on your site etc. A lot of the time people go for followers and treat it just as a mark of popularity - the bigger the better - but you want to be thinking of it as you want as many people that will be interested in your site/industry who are more likely to visit your own site, listen to what you say or even buy your products. There's always someone relevant out there!
In order to increase followers you have to really work hard. If you follow 100 people only 10 will follow you back. It is tough work but hard work is key to all.
wow, I had no idea it was 100 for 10 followers, but thinking about how it worked for me at the beginning you're right, that's how it works
You also keep in mind about twitter trends if you post or promote related things or discuss people will start following you quickly.
you should write about things that interest you, i follow a couple writers that has thousand followers and they just tweet things they find interesting
follow only those people who already follows to others this is the better way to get lots of followers.
Naturally is the best way. You want followers that are ACTUALLY INTERESTED IN YOUR TWEETS. So when you post links they will visit your website.