If you throw a tile that causes a player to have 12 pieces of the same suit revealed, and that player then picks up the winning tile, and their hand is Pure, you must pay for everyone. This is where Mahjong really becomes a game of defense. There are certain rules that you and your opponents might decide on at the beginning of each session. Minimum Hand is one of these. A mahjong hand can be complete but not worth any extra points.
Beginners concentrate on making a complete hand so that they can win something.
This often requires destroying your hand by throwing the least risky tile, especially late in the hand. Keep your eye on the Wall. When there are only a few tiles to go, do not throw tiles that are the same suit as an opponent's revealed tiles, and do not throw tiles that have not yet been thrown by anyone.