I've been looking at tons of pictures (and plans) of tiny houses, and so been thinking about how one actually lives in such a house, particularly as a couple or with children. The more I think about it, the more simplicity seems to require a lot of planning. Our current place is less than 500 square feet, and it's more than adequate right now, but it can be pretty difficult to reduce the number of things in the house.
One of the ways we've reduced (and are still reducing) our paper has been by scanning all our bills, paystubs, receipts, cards and programs, etc. I'm sentimental and so I really like keeping things as reminders of events. I spend most of my day at my work, so I keep a few special cards at work, but otherwise, we're heading towards complete paper-freedom.
Electronic storage space (aah, the power of virtual space!)
A scanner that's simple enough that you don't dread scanning
A bag for all the paper recycling (some of which may have to be torn up before you throw it away)
We've gone through much of our documents, but there's plenty more to go. Getting to the maintenance stage may be key, because once you're there, you'll just be scanning a few monthly bills or cards once in a while.