1. Provide a descriptive one line bio. What I like to do is to look at some of my followers and see who they are following. When in the followers list you can hover over the user name and a pop up will come up with that particular user's bio. If your bio is not filled out or is not very descriptive, you maybe missing out on potential followers. You have 160 characters, use them all.
2. Add a profile picture. If your Twitter account is not being used for corporate branding, add a picture of yourself. One Twit recently stated that when he asked his followers why they followed him, they came back and said it was because of his smiling profile picture. People want to connect with people and not avatars. The worst thing you can do is to not add a profile picture.
3. Use your real name. This is really important on two fronts. One is for reputation management, especially if your name IS your brand. Also if you are representing a brand, having a name behind the brand will allow people to connect with the company on a more personal level.
4. Fill out your location. Just do not put "Amongst the strawberry fields". There are plenty of opportunities to connect with other local Twits for possible offline networking.
5. Place the URL to your current blog, personal site or business. If you do not currently have any one of those, then link to one of your other social network profiles (i.e. LinkedIn). This will allow people to find out more about you, your business, or your interests.