On a long lengthwise piece of fabric I usually take my large square and my chalk marking pencil and mark down the length. I cut along this line (with a little extra for boo boos) and then I set the rest of the yardage aside. Now that the fabric is more manageable, I fold it until it will fit on my cutting board. I use my big square to cut away the selvage and re-cut the scissor cut straight and I have my border fabric.