"White Marking Pen <Fine> Clover" is what I use on dark fabric. Irons out nicely. It does take a few seconds to appear after marking, which is a bit annoying, so I might get one of the F&P white marking pencils. For lights and colors I often hear that people like the Crayola washable markers, but do they make a thin line? I use Frixion pens but don't like that the marks come back in the cold, I sometimes take quilts other places to share when freezing outside and don't like worrying about the markings.