Don't lock your keys in your home/car.

[TrainChaser]

I overhead a conversation in Seattle, two young men: "Nobody can hide a key outside a car that I can't find!"

I'm with Bob: I wear it around my neck.

 

[DrJean]

IN my convertible I always left the valet key in the door pull where it couldn't be seen from the outside but once someone broke in they would grab it with the door and not have to muck up the ignition. No one ever broke in though. (had a nasty MD slash my rag top though...)

With my van I have keyless entry. That's good to enter the van for safety but not for driving. So I do have a set inside the van as anytime someone would perchance confront me for something nefarious, I can break the fob off and throw my keys at them and still get away. (Creatures of habit, a robber will instinctively go to catch something if you throw it and say, "Catch!") I always have my keys in my hand when walking to and from Mulligan in public.

 

[Dwade81]

I keep a space key in my wallet, a spare key in a magnetic case under the car up inside the engine bay accessible from the ground if you reach up. I keep a spare key taped inside my shoe under my shoe sole near the tip top of my toes it is padded with tissue paper so it isnt hard when my toes push against it. I plan on getting a set of dog tags having one on my neck and one on my shoe laces with my allergies my name and other important data like blood type and such. the reason for one on my shoe lace is if the necklace one rips off of me or i lose it. i still got one on my shoe.