The best thing I did for myself is to make a place for all important things like my keys, watch, medicine, moisturiser etc. if I catch myself putting it down somewhere that isn’t the right place then I make the effort to put it in the right spot. For example: my keys, they have a hook by my door and one pocket they live in. They are never anywhere but those two places or in my hand and if I ever go to put them down and think to myself “Ill remember to move them later” I say to myself “of course you won’t remember, move them now”.
It’s helped massively and now I’m used to it it’s not hard to do. Of course I don’t always catch myself and do lose stuff but it happens less now.
Also trying to keep on top of clutter on sides, that way it’s easier to spot the thing that I’ve put down. Don’t get me wrong I have piles and piles of clutter that I will about once a year go through and have a clear out but I keep that stuff on shelves etc, not somewhere I would put down my phone for example