Choose a deep green hue for the base color. We used Ciate's Paint Pot in Oil Slick ($15; sephora.com).
With a nail art brush like Kiss's Nail Artist in Black ($7 for three; walgreens.com) and a steady hand, paint two lines starting from each corner of the nail, each meeting off to the side.
Paint horizontal "stitches" over each line. Don't worry about perfecting the effectthe jagged, uneven lines add to the spooky appeal.Read MoreLess