Whatever makes a woman feel sexy and confident. If a woman feels sexy and confident life is more fun, the woman relaxes and the woman radiates. It's easier to laugh and joke with a woman that isn't self conscious of her image.
Women can wear whatever they like, since it's a free country, but the only thing will turn my head in a positive way is a woman wearing traditionally conservative and classy outfits (dresses, long skirts, no cleavage hanging out). I find most modern women to be trashy.