I think part of the 'sexy' vibe comes from confidence! When I think full-on sexy, I think smoky eyes and pink lips, but red lipstick and shimmery light eyeshadow with lots of mascara is sexy, too! For a natural sexy, I like defined eyes (liner and mascara, but not much eyeshadow, maybe a highlight and a medium shade), glowy skin, and pink lips, and flushed cheeks.