In order to keep our papers straight without having to run to the (upstairs) filing cabinet every time the mail comes in, I use an expandable file folder (the kind with the handle that has a plastic latch to close it). I have labeled the inside tabs with the months of the year. In the very front, I put bills to be paid. After the bills have been paid, I label "PD 5-25-07 [or whatever the date is]" with the check number or online confirmation number. Then I stick it behind that month's tab. Everything that needs to be filed gets put behind the month that I received or paid it -- car registration paperwork, kids' medical information, etc.

Then, once a year, I go through and toss what I no longer need and file the rest. It takes me less than half an hour total to do this.

It works for me! For more WFMW tips, go here.