We all would like to answer never, but I suspect the reality is diferent for most us us. For me: #1 Treat every gun as if it's loaded at all times. Once I have visually and physically checked the chamber and feeding devices of a firearm, I will consider it to remain unloaded for the time period that it remains in my hand. If I put it down on the table, it must be rechecked when I pick it up. I also offer visual inspection to anyone else in the area before proceeding with anything unsafe with a loaded weapon e.g. feeling the trigger pull at the gun shop. #2 Never allow a gun to point at anything you are not prepared to put holes in. I'll let this one go for inanimate objects once I have verified that the guns in unloaded and it has not yet left my hand. I will not allow it to point at anything living until it has been dismantled. This rule also basically vanishes for me once the gun is secured in a holster that fully covers the trigger. I still find it polite to not point a loaded holster at anyone. #3 Do not put your finger until you are ready to fire. I will not put my finger on the trigger until I am ready for the striker to fall. I will pull the trigger when I'm field stripping at home with the gun pointed up at the roof or down at my garage. I'm not really ready to shoot either of these places, but I could deal with it if it happened. I sometimes leave my finger on the trigger when I go to ready position to get a better look at my target at the range, and I know that I need to work on this. #4 Always be sure of your target, and what's behind it. Even if it's with a BB pistol or bow and arrows, I always try to anticipate EVERYTHING a projectile could hit, even if I miss my target completely. That being said, I would take a shot at someone in my home, or possibly in public knowing the danger to others if I miss. I will accept the risk and consequences that someone might get injured by a stray shot before standing down watching someone actually getting injured by willful evil, especially if that someone is me.