1. All firearms are loaded. - There are no exceptions. Don't pretend that this is true. Know that it is and handle all firearms accordingly. Do not believe it when someone says: "It isn't loaded."
2. Never let the muzzle of a firearm point at anything you are not willing to destroy. - If you are not willing to see a bullet hole in it do not allow a firearm's muzzle to point at it. This includes things like your foot, the TV, the refrigerator, the dog, or anything else that would cause general upset if a hole appeared in it.
3. Keep your finger off the trigger unless your sights are on the target. - Danger abounds if you keep your finger on the trigger when you are not about to shoot. Speed is not gained by prematurely placing your finger on the trigger as bringing a firearm to bear on a target takes more time than it takes to move your finger to the trigger. Negligent discharges would be eliminated if this rule were followed 100% of the time.
4. Be sure of your target and what is behind it. - Never shoot at sounds or a target you cannot positively identify. Know what is in line with the target and what is behind it (bullets are designed to go through things). Be aware of your surroundings whether on a range, in the woods, or in a potentially lethal conflict.
Thank you Fr. Frog