I use Roxanne's white and silver pencils. However, I plan to use the fine blue pen on my next quilt. Sewline pencils are great for marking as you go, but if you mark an entire quilt with them, it will rub off before your get far on your quilt. I know from experience. Masking tape or blue painters tape works well when marking short lines, but not so great when marking long lines -- again my own experience. I have not used the washable crayons, but I bought some to try. I've heard good things about them. whatever you use try it out on scrap fabric to make sure it will wash out. I suggest you find a white chalk pencil -- Roxanne, Nonce, Prismacolor -- to mark the dark fabric. You can use a mechanical pencil, a graphite marker, or the blue pen to mark the light. It takes longer to switch colors, but I can promise you time spent in marking properly saves quilting time and frustration.