In the past, at the end of every year, I always had to search for receipts in shoeboxes, wallets, the car's glove compartment, and all sorts of places. Nowadays, however, I make it a habit to photograph the receipt immediately with an app. If I buy something online, I email the receipt directly to the service, which adds it to the accounting. Very practical.
I could no longer imagine being an entrepreneur without this solution. Or, I suppose I could, but then at the turn of every year, I'd be at loggerheads with the tax authorities, as an estimated 30 percent of the receipts would be missing :D