Provide tweets that inform and help people. Provide tweets that make them laugh. Be nice to others and retweet great tweets. Don't be afraid to carry on a conversation publicly on Twitter, the DM system is broken and if you try to engagement via DM I will probably miss it. So just go ahead and say it. We'll both be better for it, we'll both get a few more ticks on our Klout score, and perhaps we'll become friends.
Over time, if you yourself begin providing quality information into your Tweetstream, the audience on Twitter will notice you. The influencers always follow other influencers. It's how we work the network, it's how we communicate, it's how we build our network of influence.
We're all learning this process in our own ways. Some people like to tweet about TV shows and what food they are eating or making. That's cool, but not for me. And I'm not for everyone either. I try not to get bummed when going through the "not following you" section and learning that some of my real-life friends are no longer following me. One friend said, "I was following you for a bit, but you are insane. 90% of the time I have not idea what you are talking about. So I had to unfollow you."