Costume/clothing is important to me. I like things that are tight but not so form-fitting that there is no "jiggle." Cleavage is good. Like a lot of others have already described, I like shiny clothes like silk, latex, lycra, etc. Elegant dresses are nice, although they don't have to be super-frilly wedding dresses or ballgowns, a regular sundress can also be very sexy. I enjoy lingerie of all types, including more modest "everyday" underwear, like full-back panties and plain bras. Office and school girls are also nice.
Fantasy costumes appeal to me, although if masks are involved I prefer something like a domino mask or "catwoman" half-mask, so I can see most of the model's face (for that reason the anonymity of zentai or gimp outfits doesn't appeal to me).
I also like sexy shoes although I'm not fixated on them; mostly they add to what is already there.