How simple could it be? I am reading House Works by Cynthia Townley Ewer (OrganizedChristmas.com). I received one of those ah-ha moments with our library books.
House Works recommends that with children's things we should make it harder for them to get their things out than it is to put away. Huh? That was a difficult concept to digest. It took me a while to realize that she didn't mean make it "hard" just "harder than".
A simple change made a huge difference in the book clutter in my living room.