Mark the stitching lines on either side of the shrink sheet. Do not try to iron any wrinkels out, as the shrink sheet will shrink already! They will disappear after you have steamed.
An ordinary pencil works best. Placing the shrink sheet on a cutting mat to prevent it from slipping. Mark a simple grid (90 or 60 degrees) or make waves, stripes, circles, etc. Experiment! The closer the sewing lines, the more texture will be created. In this example I have used a 1 inch square grid.