Keys in Pants, Attached to Belt Loop... on your Person
Revived from the Dead.
When I enter or leave our Airstream, if my pants is on, my keys are in my pant's pocket. I do not carry a purse... yet. I am not among the 'New Male' Generation.
I carry my finger nail clippers in my left front pocket. (A multi use tool. Fishing or trimming broken finger nails.) My wallet in my right rear pocket. A stout handkerchief in my left rear pocket as a sweat band. My keys in my right front pocket. If any are... empty... I feel it. Routines are wonderful.
If a woman is wearing pants, put the keys into your pant's pocket.
My wife always uses a similar to a 'FallTech Steel Carabiner Clip' like used when mountain climbing. It is attached to a pant's belt loop. No... the belt loop has never fallen off, torn off or the steel carabiner failed, or keys fallen off from gravity, earthquakes, mountain climbing or horse back riding. Nope, nope and never.
Anyone who locks themselves out of their home, their trailer or their vehicle... needs to put their pants on before leaving.
Of course, I have only been doing this since I had pants. Do not recall having any keys hidden by my parents... in my diaper.