I think the best way is to let either all of them do you up or for you to pick the one or two you think will take it the farthest. You can always encourage them a bit with some suggestions. I think taylor Swift for milk is a great costume. Google it and there are some neat youtube vids with her axplaining the wardrobe. Is you hair long enough or would a wig be necessary? Check consigment/second hand shops forthem. Go for it!!!