I'm not going to do any "First, choose a name" things because you can find that all over the place. Agent Molly Jaffa does that in The Writer's Guide to Rocking It on Twitter, reprinted at Backspace. She does a little something extra by suggesting appropriate tweet material for writers--your writing and, additionally, your reading.
Then What About Followers?
Pragmaticmom (who I sort of know through Google+, not Twitter) has an interesting post, Twitter Tips and How I Got 55,000 Followers. Mia has a great deal of information here, but the point that really popped for me was the one about following and unfollowing people to increase your followers. Scroll down to the comments, and at the end you'll see I asked why to unfollow. Well, Twitter only allows you to follow so many people at a time. So you unfollow those who don't follow you back so you can follow others.
I think you have to consider what your goal is for Twitter. I originally joined for content, so whether or not people were following me back wasn't that great an issue. I was more concerned with cluttering my stream with content I wasn't interested in, keeping me from getting to the stuff I was. But rereading Mia's information about finding an audience niche and following hashtags has made me reconsider what I'm doing there.
Speaking of Hashtags
My understanding of hashtags is that they can increase your reach beyond your followers because anyone who is interested in the topic/hashtag you've added could end up finding your tweet in their stream. Feel free to correct me on that, readers.
You can find lists of hashtags related to various fields. Twitter Hashtags for Authors and Book Marketing Pros is one of them.