I have the "How to of the day" setting on my iGoogle account. Usually the "how to" suggestions are useless but today is a different story. This is something that we will all need at some point.
How to Win at Rock, Paper, Scissors
1. Watch your opponent play others.
2. Know rookie tendencies.
3. Play scissors or paper against an experienced player.
4. Look for a double run.
5. Beat your last move.
6. Use probability to your advantage.
7. Keep your eyes on your opponent's hand just as the gesture is being thrown.
Warnings:
*An experienced pro may use all of these strategies against you. They might fake you out by, say, using scissors predominantly as their first gesture and then all of a sudden using paper when you least expect it.
*"Cloaking" is when a player delays their gesture as long as possible, so that you will not have a chance to predict their gesture.
*Beware of "shadowing" where the opposing player may pretend they are going to make a certain gesture and then rapidly change it at the last possible moment.