A few tactical ideas to add to all the strategies ones other folks have suggested:

1. Add @mentions to your tweets whenever possible. @mention authors of blog posts you share, companies or publications mentioned in posts you share, individuals who might find whatever you're sharing interesting -- Force yourself to include an @mention or even two in each tweet. If you can't figure out how to include at least one, your tweet might not be all that valuable to your readers anyhow. (Unless you're offering, for example, straight-up tips based on your own knowledge.)

2. For individuals, I suggest a "notice-me list." Add folks to a private list who you want to notice you for whatever reason, and look for opportunities to RT their tweets, @reply, participate in their conversations, etc. This does two things: A. It forces you to narrow down who you truly want to connect with on Twitter, right down to individuals, and B. It helps you be more strategic about how to reach those targets.

Here's a post with more detail: http://alexisgrant.com/2012/09/19/use-this-twitter-technique-to-make-big-things-happen/

I also offer a Twitter course with daily tips like the ones above: alexisgrant.com/twitterpower

Cheers!
@alexisgrant