"Where does this live?" -- If it's in your hand, or on the counter, or on the floor, ask yourself this question. But baby steps! Pick one! I started organizing The Bachelor Pad of Mr. Moon's when I moved in by simply asking this every time I had something in my hand. Eventually, I had to pick something up off the counter or the floor, and then it would be in my hand! And then I would ask, and it would go there. If I hadn't picked it up to move it yet, then it obviously wasn't a priority yet.
* Tip: If you have something that doesn't have a home, make one that's logical for it. Some blogs will tell you to designate a basket for these things, and then find homes for them when the basket is full. Problem is, I never found a home for that basket! I seemed to do much better by simply forcing everything to find a home, and fast.
"... For now." -- This is the disaster in the making. It took me years to adopt the habit above, but this is the arch-nemesis to putting everything in its home. Mr. Moon and now the 'Rents have a bad habit of answering the above question with, "put it _____ for now." It took a few months, but Mr. Moon started to understand my approach from above and adopted it.
That sounds so civilized, but I promise you, there were a number instances of me growling in frustration and insisting that NO, I don't want to put the hammer on the bookshelf FOR NOW, I want it to live with the other tools! But after I got twice as much stuff in half the amount of space and it never took three days of cleaning in order for the house to be presentable for guests, he decided maybe he would try this "put everything in its home" as a lifestyle rather than a compromise to stop me from grumbling.
Since moving in, with the chaos of everything, I find myself occasionally uttering this phrase. When I catch myself, I try to consciously stop and talk myself through it. Why am I saying this? Where does this live? What is the barrier to putting this in its home? I'm trying very hard to remember to "put our toys away when we're finished," as it were.
Don't get me wrong though, I have struggled for a long time to be able to say "this is a project for a different day." As long as the scrubbies and cleaning supplies get back under the sink, organizing it can be a project for a different day. As long as the cleaning supplies don't have to live in the hallway until then just because the cupboard needs arranging!