If I have children and subsequently grandchildren, I will keep my three-year-old granddaughter near me at all times. When the hero enters to kill me, I will ask him to first explain to her why it is necessary to kill her beloved grandpa. When the hero launches into an explanation of morality way over her head, that will be her cue to pull the lever and send him into the pit of crocodiles. After all, small children like crocodiles almost as much as Evil Overlords and it's important to spend quality time with the grandkids.
If I burst into rebel headquarters and find it deserted except for an odd, blinking device, I will not walk up and investigate; I'll run like hell.
I will decree that all hay be shipped in tightly-packed bales. Any wagonload of loose hay attempting to pass through a checkpoint will be set on fire.
If my mad scientist/wizard tells me he has almost perfected my Superweapon but it still needs more testing, I will wait for him to complete the tests. No one ever conquered the world using a beta version.
I will remember that any vulnerabilities I have are to be revealed strictly on a need-to-know basis. I will also remember that no one needs to know.
Employees will have conjugal visit trailers which they may use provided they call in a replacement and sign out on the timesheet. Given this, anyone caught making out in a closet while leaving their station unmonitored will be shot.
I will not pick up a glowing ancient artifact and shout "Its power is now mine!!!" Instead I will grab some tongs, transfer it to a hazardous materials container, and transport it back to my lab for study.
Whatever my one vulnerability is, I will fake a different one. For example, ordering all mirrors removed from the palace, screaming and flinching whenever someone accidentally holds up a mirror, etc. In the climax when the hero whips out a mirror and thrusts it at my face, my reaction will be "Hmm...I think I need a shave."
I will explain to my guards that most people have their eyes in the front of their heads and thus while searching for someone it makes little sense to draw a weapon and slowly back down the hallway.
