Just came across 10 Tips For Managing Twitter As Your Usage Increases. This article has some great tips, some of which I’ve been doing for awhile now, some of which I recently started doing, and some of which I’m going to start doing.
Here are a few items the article mentions that are quick and easy to do:
1. Use Your Real Name In The Name Field, Not Your Username
9. Stop Your Automated Direct Message Tweets To New Followers
Obviously, the actual blog post goes into more detail, so I would suggest you check it out.