For bigger pieces of decor or furniture I've heard about the "technique" of having to imagine it in three different rooms/places before committing to it.

It won't work for everything and everyone (1 room studio appartement or something extra specific like a toilet paper holder) of course, but it can inform some decisions like getting that rug that would work both in the living room and bedroom and not the one that can only work in one place ever.

One thing that has worked for me is to work room by room, but the first thing is to get things that belong in that room there.

So my first go is getting all the random dishwear back to the kitchen.

Then all the random clothes either in the hamper or in the bedroom.

Then anything that is obviously out of place, back to the room it belongs.

Even if I stop there it's at least more organized.