1. Twitter is more than a time-waster. It allows you to actually talk about relevant stuff to relevant people. Assuming you can find them. To find them, add your Twitter stream to your signature file. My Twitter stream is here.
2. Twitter assumes you’re good both with text messaging and with keeping thoughts under 140 characters. This is inherently a good thing. More people need to keep their thoughts under 140 characters. If you take more than 140 characters to get your point across, you need to work on self-brevity anyway.
3. "To Tweet" is to send a message. Not to "Twit," Not "I’m Twitting," and DEFINITELY NOT, "Twit me." "Twit Me" guarantees a beat-down. No. Seriously.
4. 74 Tweets in a row about one topic within ten minutes is not a good use of Twitter. It is, however, a good justification to have you killed
5. Before you Tweet, remember that Tweets live forever, like anything on the Internet, and like luggage. Thou shall think before Tweeting, and thou shall not Tweet in anger.
6. Tweet about things you know – but more importantly, things that are relevant to other people, and can start discussion. Example: "I’m eating pie," serves no purpose than to automatically make people think you need to lose 20 pounds. But, "Eating pie while watching Technorati stats on "social networking" reach highest point ever" offers a good starting point for discussion.
7. Track things you’re interested in. Sending "track EWR" to 40404 will get you a message every time someone Tweets with the code for Newark Airport. I don’t recommend tracking for things like "I’m" and "going" or "social media."
8. For the love of all that’s good and holy, don’t follow someone because they’re female and you’re trying to hit on them. I’ve already heard stories of someone getting a direct message that read "Yeah, that article was really good. I like your tweets." OK, that’s creepiness x10. Don’t do that.
9. Keep this in mind: Twitter is not Dodgeball. Twitter can actually be used to a benefit. Dodgeball is really good for finding out where people you don’t like are, then going someplace else.
10. Finally, like a fine 18th century Port, moderation is key with Twitter. Tweet things that are important – things that say something. Things that make people stop and think, and perhaps even form a positive opinion of you through 140 characters. Again – "I ate pie," is not one of those things.

Happy Tweeting.
P.S.: Follow me on Twitter here