First paint your nail white for a base. I used Essie Blanc. Paint two coats of glow polish over the white. I used China Glaze Ghoulish Glow. If you don't have access to glow in the dark polish white ghosts will be fine for this design.
Using a thin small nail art or acrylic paint brush draw the outline of your ghost in black. I used China Glaze Liquid Leather.
Fill in the outer parts of the nail with black. I used my small brush for this.
Using a small dotting tool or the end of a bobby pin, dot two large eyes. Using a paint brush draw a mouth. The mouth can be any expression you desire. For this mouth I did an open smiley :D.
Now for the details! I used my small brush to dot white pupils and eye shines in the eyes and added a tongue with Essie Off the Shoulder. I went back over some of the ghosts body with white and then the glow polish to hide some small mistakes.
To bring the details together and create a seamless look seal the look with a top coat.
All done! You will have cute little white ghosts during the day and green glowing ghouls at night.