I always pre wash yardage. Why? some fabrics bleed (color runs) and some shrink. I use warm water with regular laundry det. and a color catcher, ( laundry product, designed to grab color from water, and hold it). Dry on med just like I would the finished quilt. I smooth by hand and fold for storage. When ready to use I Iron and use spray starch before cutting. Starching before cutting seems to make fabric easier to handle and keeps stretching on diagonal cut to a minimum. I do not iron before folding because I always iron before cutting to get out fold lines from storage and why iron twice? I do not like to iron!