The Four Cardinal Rules of Firearms Safety
Rule # 1: Treat all firearms as if they are always loaded.
Rule # 2: Never allow the muzzle of your firearm to point toward anything you do not intend to kill or destroy.
Rule # 3: Keep your finger off the trigger until your sights are aligned with your target and you are ready to shoot.
Rule # 4: Be sure of your target, it's surroundings, and what's beyond it.
A discussion of Cooper's Rules vs. the NRA's Rules
Kid's and Guns and
Disarming Children's Curiosity