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"Think of the space in terms of individual function zones," says Walsh.
That means all the books go in one area, and all the files have their place -- and keep like-things together, he says. "If you do that for your whole home, the idea is that if you find a fork anywhere in your home, you would know exactly where the fork lived," he says.
Set a limit on the number of a particular object that you keep, too. Whether you have 6 or 12 of something, "that's as much space as they take up," says Walsh. And if you want to add a new one, you toss an existing one. "One in, one out," he says.
"If you create a zone and set a limit, you start working with your space, rather than the volume of things you have," he says.