About a decade ago, I cut small squares of heat resistant plastic template material and added one hole with a punch. Rows 1-10 marked with a Sharpie. You could also add arrows for directions. Squares attached to piles with safety pin.
I like Dunster's idea of printing out a numbered sheet and pinning individual labels to upper left corner. (Keep It Simple, Kay) Thanks, Dunster! This method is quick, easy, and doesn't waste time or space :-)