Book excerpt: It's the essential guide to dressing to undress, from the basics of bras, panties, slips, and shapewear to the sexy extremes of corsets, sheer chemises, balconets, and bustiersÑperfect for the tens of millions of fans of Fifty Shades of Grey who are now wondering what to wear. Written by lingerie expert Rebecca Apsan (Òthe best bra-fitter in the countryÓÑNew York magazine), Lessons in Lingerie covers it all: The revelation of a properly fitted bra. How to cultivate your inner coquette. How to look ten pounds thinner. What works under a clingy dress or a sheer white blouse. The basics of shopping, cleaning, organizing. And Ms. Apsan's manifesto for change: Stop wearing underwear!