Everything in its place

The key to conquering clutter is to have, as in a kindergarten classroom, specific places where each object in your home belongs. Ideally, most of these places (wherever aesthetically possible) should be labeled. Make liberal use of plastic bins (such as Rubbermaid and Sterilite), or fancier bins made of wood, leather, or basketry where they will be visible. Target is a great place to find both kinds of bins at reasonable prices. When you finish using something, put it back where it belongs every time - just like you tell your kids.

On those inevitable occasions when you must stow something that either doesn't have a place or whose place you can't get to (e.g. it's in a napping child's room), don't think about where is a convenient place to put it. Instead, think a moment about where you would look if you were trying to find this object. As obvious as this sounds, people too often look for a place that is easy at the time they are putting the object away, rather than a place that will be easy later when they are trying to find it. And it goes without saying that if the object doesn't have a place where it belongs, you should remedy that situation as soon as possible.