I have learned that the best way to get better in anything is practice practice practice. The key in Ping Pong is to try new shots and new spins. For example, try the side spin when your playing your opponent then mix it up to top spin.
Look under the Strokes section and view the videos to learn how to do the spins. Every Ping Pong player has a secret weapon. They only use it when they need it, it could be a special serve they use or a special spin. Every player should have a trick or two to use when they are pressured and on the edge of losing the game.
Learn a few tips and apply them on your friends.