Some ideas by Katrina Gulliver
"1. Put up an avatar. It doesn't really matter what the picture is, but the "egg picture" (the default avatar for new accounts) makes you look like a spammer.
2. Don't pick a Twitter name that is difficult to spell or remember.
3. Tweet regularly.
4. Don't ignore people who tweet at you. Set Twitter to send you an e-mail notification when you get a mention or a private message. If you don't do that, then check your account frequently.
5. Engage in conversation. Don't just drop in to post your own update and disappear. Twitter is not a "broadcast-only" mechanism; it's CB radio.
6. Learn the hashtags for your subject field or topics of interest, and use them.
7. Don't just make statements. Ask questions.
8. Don't just post links to news articles. I don't need you to be my aggregator.
9. Do show your personality. Crack some jokes.
10. Have fun."
Via Steve Wheeler