Place your bills in their “to be paid” location the moment you receive them.
Once they are paid, file the receipts as you seal the outgoing envelopes. Or have a bin labeled “paid, to be filed” and make sure to file at least 1x per month. Better yet skip the filing step by paying your bills online! If for some reason you need a paper copy, either print it or request the actual copy by mail. Going paperless is helpful in so many ways because it saves time, stamps and trees!