Keep notes and always put things in the same place.
I use a big desk calendar and am obsessive enough to always put things in the same place. It really helps.

Do a little at a time.

I trust myself to forget just about everything. Staying reasonably organized makes that okay. I know where it is when I need it.

Example: the daily mail (mostly bills). I make myself put them in their place instead of just throwing them on the table. A little at a time.

I always put my keys in my purse, I never put them any other place. I have a box I put my bills in so they are all together and I don't misplace them. I would suggest you develop special places to put your things and ALWAYs put them in those places. Good luck.

i made a cork board in my room and all important papers that need immediate attention,tickets dr's visits etc go there .one pile on kitchen table bills,school notices fridge and all and every appt goes into my I phone w two alerts so i cant forget appts anymore.keep all "Cards" ins license debt in same holder inmy pocketbook always keys always on same hook

Yeah, as has already been mentioned here --

Don't put it down.
Put it away.

Quit kidding yourself that you're going to remember where you put something. You're not, LOL!!!!

Sometimes, when something really important was going to be needed later (a letter or something small), I'd put it somewhere, thinking, 'I'll NEVER forget this!!!!!

Wrong!!! Wrong!!!!

I keep an Email of things I'm likely to lose.
Stuff like:

New bottle of vitamins, top shelf kitchen cabinet.
Water bill has to be paid by 3/15. Right side of desktop.
AA Batteries, back of junk drawer.
Old pair of shoes, in back of the front closet.

I keep it in a draft to me, in my Gmail.
When the time comes that I need an item, it's usually on the list.

My house is tiny and my computer is on all the time, so this is easy for me.
If I didn't do it this way, I would have a notebook that was used for writing that stuff down, as I go.
I wouldn't use the notebook for anything else at all.

You could try saying out loud where you are putting things, as you do it.
I do that. It doesn't work, but I still do it, LOL!! It seems like the kind of thing that would work for SOME people!!!

Maybe you could try mnemonics.
There's different kinds. Look over how Wiki explains it or do a Google search on it and see if any of the tricks appeal to you.

In spite of employing all these techniques, I still lose things. Sometimes, when I do something, I don't remember that I might have trouble finding it later.

Lord knows where some of the stuff ends up. Once in a blue moon, I catch myself throwing something in the garbage that does not BELONG in the garbage!!
Who knows how many times I've done that without noticing?
I know I've been missing 2 butter knives for 3 years, now. I assume I threw them out.

Bad as I am, though, I'm much better with a portable brain. i.e., a notebook or an online record of where things are.

Good luck!!! I hope you find something that helps!!! (((((Hugs)))))

I keep a notebook on the kitchen counter and write EVERYTHING down. I also have a calandar hanging in the kitchen and write it down there also. When each chore or errand or whatever is done then I cross it off. I have to write everything down because my memory is terrible, I am constantly making notes. It is a great help if you are children in school and their activites.
In the past I have also kept a pocket calander in my purse and would write eveything down in it. That wasy if I was out and about I could just pull it out and see what needs to be done next.
I hope some of this helps you.

im too lazy to write stuff down, lately i cant spell worth a shit, which is unusual because i was the reigning spelling bee champ in school, thank god for autocorrect

dyfunfunational oriangiztion is what i do i keep track in my mind where i keep things there is no order to it i think trying to keep thins in order has you looking for things in a way that cant be traced if it is out of place but when everything is out of place your mind keeps track of it this is how i do it not sure if there is any ryhme or reason to it but in doing this i am able to find things when i look for them