D.K.
How many girls are going to be there? Have each girl bring some cool outfit, accessories from home without telling the other girls what it is. Go to the fabric store and get a long piece of red fabric, that can be the runway. Have a set up where each girl comes down the runway with whatever fashion they brought and put together. Have someone like your husband or a neighbor be the judges, with score cards and all. Have awards, you can get cool stuff from Oriental Trading or Birthday Express with like little statue awards. Rent a disco type light, dim the lights and do the fashion show with cool music your daughter helps pick out, have each girl write up their own bio and card for their fashion they are presenting.
For a fun game write down on 20 different note cards (or more if you want) pieces of clothes with discriptions. Like on a card say "red velvet mini skirt" on the next card "denim shirt with pearl buttons", "green beaded necklace"...and so on, mix up the cards and then deal out five to each girl. Their mission is to have a piece of paper, markers and so on and design whatever with the cards they were dealt, with the colors and all and share them. It can get funny as if someone gets like "blue jeans" and "polka dot shorts" they have to draw a girl with these both on...make sense?
I am NO Martha Stewart or Rachel Ray, just suggestions, sounds fun!! Have the latest teen fashion mags around too for fun.