Rule # 1
All firearms are loaded. No exceptions! Always assume that any and all firearms are loaded at all times. Perform a chamber check and a magazine check each and every time you pick up a weapon. When a weapon is handed to you or you hand off a weapon, perform a chamber check to confirm that the weapon is not loaded.
Rule # 2
Never cover the muzzle of your firearm with anything you are not willing to destroy. This includes everything that you can think of: a person(s), your feet, hands or others, a dog, cat, TV, car, couch, chair, or simply a spot on the wall.
Rule # 3
Keep your finger off of the trigger (and off the trigger guard) until you have made the command decision to fire. This should be rule number one. Find and locate a reference point on the weapon and know it. This should be a location outside the trigger guard, not the magazine release, but simply a spot that your finger is on prior to trigger placement. Negligent discharges only happen when the trigger is pressed. A firearm is a mechanical device that requires a physical action to "fire". You cannot tell it to fire; the trigger must be pressed. So, keep your finger off of the trigger and the trigger guard.
Rule # 4
Be sure of your target and what is behind it. You must be aware of the berm, barrier or back stop. Never shoot without assuring that the round you fire down range can be stopped by an intended body or a cover that is sufficient to the ballistic caliber and cartridge you are shooting. Know what is behind your target at all times. Equally important, you must guarantee your hits. If you miss the target then you
have missed your guarantee that the bullet will be stopped. Do not shoot at sounds or a target that 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 at all times including range, desert, urban, interior, and all environments which you may be confined.