The document outlines 5 common mistakes that businesses make when using QuickBooks accounting software. These include: 1) Not reconciling bank accounts regularly, 2) Not using keyboard shortcuts, 3) Not backing up QuickBooks data, 4) Not upgrading to the most current software versions, and 5) Entering bills and then writing checks instead of using the "Pay Bills" feature for payments. The document stresses that while mistakes are part of learning, businesses should learn from these common errors to prevent problems in using QuickBooks down the road.