I only use it if the pieces I'm working with a very small. I always lightly spritz the fabric with water then press to see how stiff the fabric might be on it's own. Seems different manufacturers put different amounts of sizing in their fabrics during production anyway. If it's not stiff enough after a quick press with the water, then I lightly spray will starch, giving the fabric a few seconds to dry a bit before pressing, so as not to take a chance on scorching-especially with the lighter colored fabrics. When I do use starch, I spray the back side of the fabric, never the front. I don't use a special starch, so sometimes there is a very slight amount of residue that I want to avoid having on the right side of the fabric.