"Use it up, wear it out, make it do or do without" is a motto that I've written up on a card and taped inside my coat closet door as an affirmation for myself.
It's a multi-tasking motto for both de-cluttering and for frugal living, in my experience. By de-cluttering, I find out what I have and how much of it I have, and it all goes into one place. Then "use it up" kicks in. Two very different examples where they work well together are office supplies and dessert ingredients.
I have two places in my home where I keep pens, markers, and pencils: the kitchen junk drawer and an old coffee mug on my home office desk. When, for instance, Sharpie markers would go wandering, I'd never be able to find one and I'd go out and buy more. That both increased the clutter and cost me money. But now that they're all organized and I have to look in only two places for the marker I need, I can wait until they've worn out before I spend more money on them.
As for dessert ingredients, I used to have them scattered among several shelves and cabinets. I would never know what I had on hand. Half the time I'd start making something and suddenly discover that something was lacking, so I had to run to the store or waste the dessert. The other half of the time, I'd buy things ahead of time, only to find that I already had three opened, partially finished packages in the cabinet. That's especially problematic if the item, like walnut pieces, can go rancid. But now that the dessert things are organized, the "make it do or do without" kicks in. I can easily see what I have on hand, and I can make something from that rather than running to the store at the last minute for an ingredient. That saves me money, because I try to buy my groceries when they're on special sales, as much as possible, and you can't do that if you're in a position where you can't wait a few weeks for that special to come around again. (And, of course, there's that problem where you go to the grocery store for one $3 item and come out with two sacks and your wallet $30 lighter.)
