In Charla Krupp's world, there are two kinds of people, OLs and Y&Hs. Which is just fine, if you like your particular cubbyhole.

But with so much money spent each year by women trying to look more “;Young and Hip”; than “;Old Lady,”; she's written the definitive head-to-toe, how-to book on the subject without mincing words. Its title? “;How Not to Look Old.”;

With a title like that, you might be expecting a shallow, ageist work, but the book is full of empowering strategies for trying to look relevant in ways that don't involve Botox, surgery or spending a lot of money on expensive clothes or makeup, which registers as OL and desperate.

“;It's not just about style for style's sake, and not about looking hot to get a guy,”; said Krupp, a former beauty editor at Glamour magazine and senior editor at InStyle, in a phone call from New York. “;It's about looking younger so you can stay employed. When I was writing the book, the economy wasn't in the shape it is now, with so many people out of work who need to meet people and need a kick start.”;

Her focus is on looking appropriate and comfortable in your skin, which is very Y&H.

Once the book was published, Krupp said many of the people she works with wondered why they didn't think of the idea first.

“;Every magazine is full of tips for looking younger, but no one put the information together in one book for women over 40. More than wanting to look chic or sexy, they want to look young.”;

She said the book has been well-received, and at book signings, she's always asked to sign gift copies for other women. “;It's a real girlfriend to girlfriend gift.”;

Looking Y&H starts with taking a good look in the mirror to see if you're stuck in a time warp. Every decade has an identifiable aesthetic, and if you're still wearing big, overworked hair, well, that's OL. If you're still wearing matte makeup, that's OL.

Getting makeup and hair right doesn't require spending any more money than you already do on maintenance, but may simply require a change in color or style, not as a matter of mindlessly following trends, but to remain current. Such changes also address the physical aspects of aging. With technological advances have come new products, such as creamy shimmer face colors, that subtly add radiance to dry skin, helping to mask and deflect attention from wrinkles and other problem spots.

Krupp has already finished her next book, still untitled, which will focus on fashion strategies for looking young without looking ridiculous. Although some men have asked for help, she said, “;I know much more about women's fashion than men's fashion and I think it's best to stick to what you know. Besides, men have Viagra. That's enough.”;

IF YOU'VE ever wondered how some 50 -year-olds can pass for 35, and how some 35-year-olds can look like they're close to retirement age, photographs on these pages demonstrate a few of Krupp's tips for how not to look old:

Hair: One thing that dates women the most is their hair, whether it's in the cut or color. In Krupp's view, nothing ages you like hair that's too dark. The general rule, she writes, is “;The older you get, the lighter you go.”; The reason is that hair that's too dark emphasizes lines on your face by casting shadows into them. If you don't want to color all your hair, try going two shades lighter on the hair that frames your face. Cutting angles and layers around the face also is Y&H.

Lips: One of the quickest changes you can make is trading dark or red lipsticks for lighter hues. Krupp writes, “;Iconic Palmoa Picasso pulls off fiery red with pizzazz, but don't kid yourself—it's tough to wear! Darker lip colors emphasize the dark circles under your eyes. And the darker the color, the thinner your lips will look.”;

Clothes: If you've watched any TV makeover show, you've heard the rule against looking “;matchy-matchy”; or overdone (see model at far left), which is OL. The secret to Y&H dressing is effortless chic, the opposite of looking like you worked hard at getting every detail to match. This is not to suggest sloppy is in. I'd call that young and tragic. It just means loosening up a bit. “;Don't shop for head-to-toe outfits,”; Charla Krupp advises. “;Instead, buy a fresh new piece that speaks to the current fashion moment, and make sure the color and style mix well with at least two pieces you already own.”;