Put on a floor-length dress with long sleeves, preferably in solid black, white, yellow, red or brown. Wear a floor-length skirt and long-sleeved shirt in the same colors if you don't have a dress.
Make a tunic to wear over the underclothing in a contrasting color. Find a piece of material, such as a tablecloth, sheet or old curtain. Cut it to 3-feet-by-4 feet. Then, cut a 7-inch circle out of the center of the fabric for your head. Or find an extra-large solid-colored T-shirt or blouse, and cut out the neck and sleeves.
Put the tunic over your head and cinch it at your hips with a leather or rope belt. Trim the sleeves of the tunic as needed so they end anywhere from your shoulder to the middle of your upper arm.
Wear a wimple on your head. Cut a piece of lightweight material about 2 feet square. Place it over your hair and fasten it with a thin strip of fabric tied across your forehead. The wimple should cover your ears and neck when worn.
Choose thin leather slip-on shoes to complete the medieval peasant girl outfit. Go barefoot for a truly authentic peasant look, as many peasants did not wear shoes in warmer months.
Accessorize with a woolen cape that reaches down to your knees. Attach it around your neck with a simple metal brooch.
Choose a floor-length underskirt, preferably in yellow or white. Wear a matching long-sleeved shirt to complete the underclothing for a noble girl.
Cut a slit in the front of another floor-length skirt in a contrasting color. Trim the bottom of the skirt with lace, beads, sequins or sew-on faux gems. Wear the overskirt so that when it separates in the center, the underskirt shows through.
Cut the neck and sleeves out of a brightly colored oversized blouse or shirt to make a bliaud, or overtunic. Trim the edges of the sleeves with lace, ribbon, faux gems or faux fur for an authentic medieval look. Put the tunic on, and belt it at the hips with a wide, decorative sash or belt.
Add a mantel by pinning a long, flowing piece of material to one or both shoulders with a brooch. Embellish the edges with lace, faux fur or beads.
Make a tall, conical hat by forming stiff poster board into a cone. Staple it together, then trim it so it fits on your head. Decorate it with glitter, faux gems and lace. Attach a silky piece of fabric to the point of the cone. Keep it on your head using pins and a strip of ribbon tied beneath your chin.
Wear thin slip-on shoes, beaded slippers or soft leather boots to complete the look of a wealthy girl from the Middle Ages.