Grey Pleated Skirt Ideas Of What To Wear For A GIRL Slytherin Hogwarts Costume?

Ideas of what to wear for a GIRL Slytherin Hogwarts costume? - grey pleated skirt

I have a gray folding mini-skirt. I would have the white socks, black shoes recently, a blouse and a green tie. Has anyone ideas how to improve this, or ideas for accessories?