UPGRADE HER UNDIES

Step 1: Size her up
The first rule is to get your girlfriend something that fits. Do some reconnaissance in her panty drawer, and note the average size of both her bras and panties. If you forget to bring these numbers with you to the store, remember this much: When in doubt, go smaller. On the top and bottom. Why? “Even if I’m miffed that the size is wrong, I’ll be happier he thought my tush was a model’s size 4 rather than four sizes larger,” says Rory, 27. And if the bra is too small, she’ll be more grateful to spill out of it than to be embarrassingly unable to fill the cups.

Step 2: Blow a small fortune
If you want sex this year, do not buy her cheap lingerie. Your first and only stop should be a specialty store that displays bras on puffy pink hangers an inch apart from one another; this underwear will be of notably better quality than those sold at stores ending in “-Mart.” As for brands, always shop for labels that make you feel like a jackass saying them out loud, like Agent Provocateur, Dolce & Gabbana, Cosa Bella, La Perla and La Petite Coquette. You won’t know the difference…but she absolutely will.

  

Step 3: Feel it out
You might find leather zipped lingerie and matching spike-heeled boots hot. Women find them scratchy and confining. Texture can make the difference between what she’ll wear once as a sexy gag and what will change her undie habits. If you ever want to see that cute ass again, follow this guiding principle: Imagine that you have to sleep on sheets made out of the same material, in which case cotton, silk, satin, rayon, Lycra, and lace will last her through the day and get you through the night.

Step 4: Take it easy
No girl can become a Victoria’s Secret model overnight. But better she be half-naked in a conservative bra and panties than all covered up in flannel PJs. Sexify her gradually: If she only wears cotton bras and undies, surprise her with a sexier set for no reason. (Stores you actually shop in, like Banana Republic, now make intimates that won’t make a shy girl blush.) If she only wears boxers and T-shirts to bed, buy her tap pants and a low-cut, tight-fitting tank to wear with it. Progress will be swift.

  

Step 5: Cop her style
Buy in line with her taste, whether it’s romantic, sexy, classy, cute, or slutty. Choose panties bound on the sides by more than two scraps of dental floss, chemises that drift delicately over her backside, or a pair of tap pants. Second, encourage skin baring up top. Buy an underwire or demibra for a small-chested woman, to best display her assets. If she’s voluptuous on top, let her bare it with a plunging neckline or dress up her tits with lace.