red. Studies show men even tip waitresses more when they are wearing some sort of red.
Red actually looks garish to me in some hues or on some skin tones... Nails glazed in a hue close to the woman's natural skin/nail color, but tinted with more warmth (adds a 'healthy' glow and shine), and lips more tinted with hue rather than outright painted. Again, pinks, tinted with reds, oranges or golds according to skin tone, to add to that enhanced allure look. I guess the 'desirable' style that stands out to me is more natural-feminine or elegant, rather than sensual.