The costume had to be warm, because it often snows in Colorado on Halloween. And we didn't want to have to paint too much of her body, because of the expense of the paint and because it gets itchy.
We started with a second hand choir robe as the base. Angel wings and werewolf teeth from a costume shop. Krylon "make it stone" paint in "black granite" (grey for the robe) and "obsidian" (black for the wings).
Step 1: Painting the Costume
Step 2: Face Paint and Under Layer
I ordered Palmer face paint in black and white online, and applied with make-up sponges and a pastry brush. The pastry brush was GREAT for painting the hair. Highly recommend that.
We mixed a base grey, then sponged bits of black over her face and outlined her eyes with black eye liner. Even I was surprised at how well the effect worked.
Step 3: "Blink"
You may want to add some sort of rigid structure with a coat hanger or something, if you care. But as you can see, once she had it all on the effect was great! Good enough to scare everyone in the neighborhood.