I did this mani on my sister the other night. It turned out pretty adorable despite it's spookiness! For this one, I used two coats of white on top of a base coat and then used a special black polish to add the details.
This polish, by Witchcraft, comes in several different colours and is available at Shoppers Drug Mart. It has a very skinny and long brush that is pretty versatile for adding details to your nails and is a nice alternative to a toothpick or small paint brush. It has been very handy having this polish in white and black to pain images onto the nails or just for adding outlines and accents.
I finished this mani off with a top coat and then hid under my covers. Boo!