Agree ... either pencil in the seam lines or use the Frixxion pens as they will erase out when you heat set the signatures.
I have had no luck writing on the fabric even when pressed to the freezer paper ... it seems to free itself from the waxed coating and then it's just a slippery mess.
What I do, is spray the fabric with 505 and stick it to paper and cut to size, for crisp edges. Holds it tight, for the signing, and I stitch with it on, as I would for PPing.
For markers you can use Sharpie Extra Fine markers. You can get a whole assortment of colours which would make the signatures a little more interesting ... plus some may include a drawing with their siggy if you provide the tools!
Be sure to remember to heat set all, after the signatures are done.
Last edited by QuiltE; 10-16-2012 at 08:48 AM.