Each color of duct tape should indicate a room or “zone” in the house. Assign each room in your house a color. For instance, all my kitchen boxes received a red piece of duct tape. After I finished packing a box with kitchen items, I would put a piece of red duct tape somewhere on one of the four sides of the box. Do not put it on the top, that doesn’t help when all the boxes are stacked a mile high in the moving van or shipping container. Put it on one of the sides so you will see at first glance.