A good window! One of the quilt shops I go to is situated where there is no natural light. Difficult to match fabrics. If no window is available, then have an Ott light for customer use. Also, have a variety of fabrics. My favorite shop for classes carries all calico/30's/vintage look. I'm in to contemporary. Still take their technique classes as the skills can be used with any type of quilt, but I usually donate or gift the item made from their kit.