Perhaps this violates the common sense rule, but I really don't see many people do this.

I won't lock anything except by physically inserting a key into the lock and turning it.

I always used to lock doors the 'easy' way: by hitting the switch or button on the door as I headed out, but too many times I ended up locking my keys inside. Since I started doing it the "hard" way I have always had my keys in-hand when locking the door.

In the beginning, I would often (with the keys on me) forget and accidentally use the inside switch. In order to enforce the correct habit, I would unlock the car door and re-lock it using the key. For the house doorknob, I simply put a piece of double-sided tape on the switch—not to keep it from turning, but so that I would feel the tape and remember not to lock it that way.

BTW: Yes, I drive a car without power locks. . .