I like using Frixion pens when I can, but I use them where marks cannot be seen as a precaution. I have used washable blue pens and white chalk with success. The dollar store sells battery operated toothbrushes for a dollar each. I dip mine in some water and then wipe off the blue marks. It also does a decent job in brushing off the white chalk marks. The bristles are soft and do not hurt the fabric.