You can mark grid lines directly onto your quilt, but creating a grid with painter's tape makes the task much faster, and the tape will not leave a residue on your fabric. Visit any home improvement store to purchase this blue tape, which comes in a variety of widths. Your grid can be configured into squares, diamonds or cross-hatch shapes -- any straight-line design that you can imagine. Each piece of tape can be used multiple times before it begins losing its ability to stick to fabric.