Step 2: In With the New

Lingerie is a personal matter, and so is the amount of lingerie you choose to own. For the minimalist, a few sets of cotton panties and stretchy camisoles are enough; for the collector, lace-trimmed, leopard-print teddies are just the beginning. But if you want to simplify your life, you need: a) enough plain, everyday underwear to get you through the week without having to do laundry; and b) the kind of special-occasion lingerie that answers questions like, "What am I supposed to wear under that?" Between what you own and what you're going to go out and buy, you should have:

Seven simple, comfortable bras. For work and weekends, you'll want seamless ones that look smooth under T-shirts. Get a couple in black and a couple in a shade that blends with your skin. "Nude is more modern than white, and more practical," says Bantivoglio. ("Once you've worn it, you might never feel like you can get a white bra clean enough," says DiFalco.) You might also want a camisole to rotate in once in a while (Hanro makes high-quality, ultra-comfortable cotton underwear).

One black strapless bra for formal occasions and one nude racerback bra to wear under tank tops. You might also (depending on your needs) want to invest in a backless bustier to wear under an evening gown and one full-body girdle that combines a bra, a tight-fitting bodice, and control-top panties that extend to the middle of your thighs.

For evenings and romantic encounters, look for pretty, lacy push-up bras in a variety of colors, and buy the matching thongs or panties, depending on your preference (La Perla, Le Mystere, and Victoria's Secret all make pretty sets). Splurge on one silk chemise that hits your legs at mid-thigh. "It has to be sexy, but not too specific-looking," says Bantivoglio. "So if you bring it out again a week later, your boyfriend won't say, 'Oh, I've seen that on you.'"

The rules for panties are less specific. Some women buy matching bottoms for every bra and refuse to separate sets. But it makes more sense to stick with the neutral black and nude formula and buy a variety of interchangeable thongs (to wear with tight trousers), bikini styles (to wear with clothes that ride low on your hips or snug shirts that expose your navel), and boy-cut panties (which offer both coverage and freedom from panty lines).