Rule #1: Treat every weapon as if it were loaded. Even if you are sure the weapon is not loaded, you still treat it as if it is!
Rule #2: Never point your weapon at anything you do not plan to destroy.
Rule #3: Keep your finger straight and off the trigger until your sights are on the target.
Rule #4: Identify your target and what is behind it. Never shoot at anything that you have not positively identified.