Designate a place in every room as, “the place I put things.” Use positive reinforcement to train yourself to put things down in that space. Every time you use a drop zone, give yourself an attaboy/girl. It needs to be big enough that it can hold a few things, keys wallet, cell phone, but not so large that things can get lost in it. You don’t want too many drop zones, but you need to have one always handy. Keep them uncluttered when possible so that they’re always available. Dissuade the people in your life from “cleaning up” these spaces. Now, when you lose something, you’ve got a good chance of finding it by checking all your drop zones.
Well my drop zones evolve to piles, and then there’s just piles of stuff. But at least I always have a rough idea in which pile the currently desired item is.
I think a good drop zone is limited in size, so it just isn’t possible to endlessly pile up stuff.
Right now, I have a small table, which collects all those random things - and when there is no more space to put another thing, I put everything I didn’t use for some time into boxes.
Now there’s boxes full of stuff, but the room doesn’t look cluttered or messy. Progress!
And the next step would be to regularily sort through those boxes and throw stuff away… Someday. For sure.