A few years ago, I came upon this method of organizing all of our monthly receipts and pertinent paperwork. I must have read about it in a magazine, most likely Real Simple (great magazine!).
Then we put all of our grocery receipts, bills, car repair paperwork, etc, behind each tab as the month goes on. It is really easy to find a specific receipt if a need to make a return. I also don't put the receipts in there until I have recorded them in my budget for the month.
This particular accordian file had an extra space in front which I like to keep important paperwork that isn't related to a specific month, like prescription information, special notices, etc.
Now I'd hate to have to open it every time I use it, as it would no longer be convenient, so I slide it into an area it can stay open on my "desk" (kitchen counterspace reserved as my desk).
At the end of the year then, and of course the file is FULL, I close it up, write the year in permanent marker along the spine, and put it in a box, along with the others from prior years.
This is what works for me. For other ideas, see We Are That Family.
What works for you for your regular paperwork or budgeting?