The mark be gone pens are my choice for light colored fabrics - sometimes when they dry they will come back. To avoid this problem mix a tsp of baking soda in a pint of distilled water. Learned this trick from a chemist, something to do with the mineral content of the water. She was also a quilter.
As for dark fabrics, I go for my tailors wax piece. Always test on a edge or something when marking a customer quilt. If there is any poly content in the fabric there will be a faint evidence of the mark. Remove this with your iron. If you don't have it, get a few friends to go in with you on a box of the stuff. I get it from Atlanta Thread and just a piece or two lasts me for years. Its the giant one. Don't buy the colors - don't come out. The company seems to have merged with another and the wax is on sale. I teach my new customers about using the wax and give them a sample piece when they first start coming to me for quilting.