Wash your hands, wash your hands, wash your hands. One of the frustrations of working in the 90's is to come back from lunch and find voice mail messages you can't understand. People talk too fast, they talk too slow or they just talk and talk until they get cut off - often before leaving their numbers. It seems that many people who leave voice mail messages haven't determined why they're calling, what they're trying to say or what they want you to do when you get their messages. Don't start leaving your message until you hear the beep.
Many people start talking before the outgoing message is finished.
Make your message as short as possible. Be clear and concise and get straight to the point. Before you start speaking, take a deep breath so your lungs are full of air. This will give your voice more depth, power and authority. Make your voice sound interesting.