If you feel sexy, you will look sexy. Pick the one spot on your body that you love the most.
-If it is your legs, invest in a good old-fashioned garter belt and thigh high stockings. They NEVER go out of style, but are seriously sexy. Plus they can be paired with a skirted teddy or ensemble if you are wary about other parts of your body.
-If you love your tush (and if so, I'm jealous) go for those cheeky panties and some heels to give it that added oomph. If you want to cover your tummy or another area you can wear something loose but just sheer enough on top.
-And if your "girls" are your favorite - play them up and let them shine! Even just having a deep cut nightgown or robe that is longer will be beautiful, and with just enough showing I'm sure it wont last for long.
If you are still not feeling confident, I recommend looking into "Boudoir Photo Shoots." There are so many companies and photographers doing this now. It is designed to make women of all shapes and sizes feel unbelievably sexy, plus it gives them the proof in a photograph! The day usually consists of a stylist that selects just the right outfit and setting and then does hair and make-up to match. They are private, professional, and a total ego boost. Just make sure you don't find a photographer on Craigslist