Golden Rules of Weapons Safety
This is THE GOLDEN RULE of weapons safety. All other weapon safety rules fall under this one simple yet powerful rule. Keep this rule in mind at ALL times when handling any firearm.
Firearms should always be treated as loaded, whether you believe them to be unloaded or not. This means even if you just checked the firearm and found it to be unloaded, you should STILL treat it as loaded. You've heard it before, "I thought the gun was unloaded!" after accidental shootings - people make mistakes, don't let yours be a fatal one!
Basically, if you care about something, whether it be a person, an animal, an object (a tv, etc.) then DON'T point your firearm at it! Since all firearms are always loaded (see rule #1), it can always potentially discharge unexpectedly (known as an Accidental Discharge). A firearm is only a mechanical device, and has the potential to fail at any given moment, safeties included. Accidental Discharges are scary and happen even to the most experienced firearms handler, but if you follow this rule no harm will come to anyone or anything important.
For more specific rules of hunting and firearms safety, please see the IHEA Today's Hunter Hunter Safety Manual (PDF 34MB).