I mark after I sandwich. Just the way that seems to work best for me.

I mark before, becasue I mark for others to quilt and it is better to have it done before we start. If I am the only one quilting on something, I can mark as I go! :lol:
I find it easier to mark on a hard flat surface as well.

You trace your quilt pattern ( say..scallops) on paper sheets with peel off backing, cut out, peel off back and stick on your quilt. Then sew around scallop edges. You can peel off and stick again as you go. Contact paper works too. Her book gives you lots of designs to trace.