Here is a post of mine I copied from a previous thread:
One really cool way to use them is on glossy paper stamp an image, then color in with metallic pencils. Then, rub the image with the paper towel. The metallic pencil acts almost as a resist and some of it rubs off, leaving an antique look to it. Some of the color is left, but not all.
You can also trace through a brass stencil onto glossy cradstock, brayuer over, and wipe off as a different resist.
I also use it with the bottlecap technique to color in the image before ep is added-it is almost as if the metallic pencils melt a bit in the oven, softening the coloring a bit. It is hard to see, but I used them in both bottlecap techniques I have posted om this site (1 In the Wild, 1 Classic Convertibles)
If you use white craft ink and let it dry (you can speed up the drying with a heat gun) you can color over the whole piece with metallic pencils-looks very cool. I think Beckitty shared that idea with me at a meeting.
and here is a thread about them with more ideas:
Forums at Splitcoaststampers
Enjoy!