For Soso: A prison jumpsuit in a khaki color, a black, shoulder-length bobbed wig, and black slip-on sneakers.
For Poussey: Poussey's look is the same as Soso's, only she usually just wears a white tank top instead of the full khaki shirt, and she rocks a close-cropped haircut. If you want to go the extra mile, make little badges with the characters' names on them to stick on your pockets.