For Sara: A red wig pulled back into a ponytail, with a thin braid hanging down on one side. Sara is extra fond of leather, so bust out your leather pants or leggings and wear them with a leather peplum top (which you can feel free to adorn with faux plates of armor). Get a bow and arrow to drive it home.
For Ravenna: A gold cape (go above and beyond by gluing some feathers onto it and spray painting them gold), a gold crown, a blond, braided wig, and a gold dress. Also, get a little raven figurine or stuffed animal to perch on your shoulder.