Never point the muzzle at anything you do not intend to shoot. In an apartment complex, with people living in every direction around you, up, down, sides, this is challenging. IMHO, in a cluster of apartments, gun should never leave a holster, except in an emergency.
Never put your finger on the trigger, until your sights are aligned, and you are ready to shoot. Keep your finger off the trigger!
Keep your guns unloaded, until you are ready to use them.
Additionally, keep all guns, unloaded, locked up, in a gun safe. Inside a sock, in the sock drawer, is not good enough. keep all ammo, locked up, in a separate location, not with the locked up guns.
If you have a imitate peril handgun, you want ready at a split second, keep it on your person, in a level 2 or above holster, or keep it locked up in a small, dedicated for nothing else, safe.
If you own two guns, and no safe, sell one, and get a safe. If you own one gun, and no safe, sell it, and buy a dog, or buy a safe, and save up your money for a gun.