Safety First!

Do not swing your club until you know that others in your group are at a safe distance. Likewise, keep your distance when others are swinging. Be aware to steer clear of trouble.
When practicing your swing, never swing in the direction of another player. There may be pebbles or twigs or other matter in the grass that could fly up and strike a playing partner.
Do not hit the ball until you are certain that the group ahead of you is out of range.
If your ball appears headed toward another player or another group, give them a warning by yelling out, "Fore!" (an internationally recognized alert)
Observe the safety suggestions posted in golf carts and drive carefully. Golf etiquette requires keeping your cart off the grass as much as possible. (see golf cart safety for more)
Never throw clubs in anger. In addition to being rude and childish, it could also be dangerous.