I use a mechanical pencil and lightly mark the lines. To remove them, I use an artist eraser (the kind that is soft and doesn't leave the little thingies behind). You can find these in what looks like a pen, but has a long soft eraser that you can replace when it is worn down. They have them at Wal-mart or office supply stores. They remove the pencil marks completely, and you don't have to press hard to remove them.