One of the things you could do was pay certain types of widely used paper invoices. When I was brought on, the UI for this was just a standard HTML table with labels and input boxes. I decided to build a prototype with a paper invoice image as the background and a textboxes places where the numbers appearred on the paper invoice.
When people paid the invoice, they would have the paper version they had received by postal mail next to them. Now, their mission was to enter the numbers so they would end up with a visual one-to-one copy of the paper invoice on the computer screen. It made it easy for everyone to figure out which numbers to enter.
People embraced this immediately, and all forms were changed to follow this principle. All banks implemented it in their banking apps and still use it today.