Medusa's hair is kind of messy and crazy so this part doesn't have to be perfect – or even close to it. We just put Saff's hair up in a few loose braids and then pinned them to the top of her head. We added in some plastic snakes and secured them with bobby pins as well.
There are several ways you can do Medusa Makeup, but we did a basic green coat and then added white Manic Panic Goth on top.
Add some scales with an eyeliner roll-on.
The actual costume is a cream colored pillowcase with a slit cut in the top and side for arms. :) We tied a few pieces of yarn around the waist so it isn't SO big. You could also cut and sew it but I wasn't putting that much effort into it.
Notes
You can create this Medusa Costume look for FREE if you have these items on-hand, or for as little as $3 if you have to buy some of the supplies.