Start the conversation by asking some open-ended questions. Limit the number of hypothetical questions because you don't want to turn it into a job interview. Remember, it's a conversation not a trial or interview.
Read the newspaper or a magazine before a date or event. Twitter is a great way to quickly get on top of current events. Avoid bringing up the weather or traffic. If you're going to a party, know your audience.
Monopolizing the conversation does not equal good conversation. The art of chit chat is like playing tennis — a nice steady back and forth.
Leave when the conversation is at its height for the best impression. If you're in a boring conversation, you can get out gracefully by excusing yourself to go to the bathroom, refill your drink or grab more food.