Joanie,
I don't use stencils like I used to. I buy netting -- the type used in tutu's and draw my quilting motif on that with a Sharpie (fine point, please). You can cut the netting into pieces, make long pieces for borders, and they are virtually indestructible.
After you have the motif drawn, pin it, tape it, hold it in place if it is little, to the quilt top. Using a washable marker, trace over the Sharpie lines... voila! the motif is on the quilt top.
I tried the double bleded Xacto knives, which I found to be a pain in the butt. Besides, quilt stencils are too FAT and you get inconsistencies with the stitching. With the tulle (netting) method, and a fine washable marker, you are assured that the markings are where they should be.
Hope this helps.
Anita