Knowing the NRA rules of gun safety is of paramount importance. You already know the “Big Three”: 1. ALWAYS keep the gun pointed in a safe direction; 2. ALWAYS keep your finger off the trigger until ready to shoot; 3. ALWAYS keep the gun unloaded until ready to use. These rules will keep you and others safe while you're in the field with your firearm.
You may have heard of a different list of four gun safety rules, too. They're known casually as the Gunsite Safety Rules: 1. All guns are always loaded; 2. Never let the muzzle cover anything you're not willing to destroy; 3. Keep your finger off the trigger until your sights are on the target; and 4. Be sure of your target and what's beyond it. These rules will also keep you and others safe when you're in the field.
Which ones should you use? Either or both, really; whichever is easiest for you to remember consistently. The biggest risk to your safety isn't in your hands, it's between your ears. New gun owners are at risk of being distracted from the rules by inexperience, while experienced gun owners are at risk of being distracted from the rules by complacency. That's why we implore you, dear Reader, to watch this video even if you're pretty sure you already know everything we're going to say.