"Today, everybody is young," says Betty Halbreich, veteran personal shopper for New York's Bergdorf Goodman specialty store.

In her 22 years of retailing, Halbreich has helped generations of customers — no matter what their age — learn how to put together their wardrobe. "Women today don't want an age put upon them," she says. "They're always looking for style."

Halbreich, who has co-written the new book "Secrets of a Fashion Therapist" with Sally Wadyka, a senior editor at Vogue, says she has witnessed an interesting phenomenon in the last few years when it comes to mature women and fashion.

"Most of these women are very meticulous about their appearance," she says. "They're actually some of the best-kept women I see.

"I think it has a great deal to do with how they grew up. You wore hats and gloves if you even stepped out of the house. The same goes for men who all wore coat jackets and hats."

Today, Halbreich sees these same men and women "keeping it up," whether they're going to the country club for a game of bridge or walking the dog in the neighborhood.

"Even when they're in running shoes, they still have their hair and nails done," she says.

Despite the trend toward more casual dressing, Halbreich finds that most older women still like their wardrobes and appearances to be put together.

Here are some of Halbreich's secrets to smart dressing — whether you're retired or not:

*The most important rule to keep in mind is that casual doesn't mean sloppy. You can dress in casual attire, and yet still look completely polished and pulled together. A little makeup plus well-groomed hair help.

*Never underestimate the power of a basic blazer. Toss a classic black or navy jacket on — even over simple jeans and a white T-shirt — and suddenly you look more professional.

*Wear denim in pieces besides jeans. A crisp, unfaded denim shirt can bring a black pantsuit down to a more casual level.

*Jackets that aren't really jackets — like an unconstructed, long knit cardigan — can soften up your look.

*A T-shirt-style dress (as long as it's not too short or clingy) can be the perfect casual day solution. Dress it up slightly by tossing a jacket or cardigan on top.

*Think about accessories like a sportier watch or some chunky link bracelets. Use jewelry to change your look from sporty to dressy. Also, don't forget color. Halbreich has found over the years that most gray-haired women shy away from gray flannel colors.

"I tend to agree," she says, "but you can still wear grays; you just need to accent them with a flash of red or purple or yellow. I personally don't like gray right up to the face. I've never seen anyone look good in it."

While gray flannel trousers are a classic in many women's wardrobes, Halbreich suggests topping them with a suede jacket or a leather vest over a soft silk blouse.

"The right accent can be as much about mixing textures as it is about mixing colors."

*You don't need to match your clothing to your eyes or hair, but be aware of which shades complement your features. Halbreich's favorite color?

"I've never known a woman who didn't look good in pink. I think it looks clean and sensuous on everyone."

*Classic, man-tailored trousers can be safely mixed with most jackets, sweater sets and even simple T-shirts.

*A full skirt worn with a slouchy, unstructured jacket will make you look eight months pregnant no matter how thin you are, or how old.

*Dressy and casual are a tough mix. A soft wool cardigan can look great with a taffeta evening skirt, but don't try to top off a wool gabardine skirt with a taffeta jacket.

*Makeup is a wonderful accessory — and just like fashion, the "in" colors seem to change every season — so investing in a new lipstick is probably the simplest and least expensive way of picking up on a new trend and making yourself feel stylish.

*Another way of updating your wardrobe instantly is with shoes.

"Your basic shoe wardrobe should allow for at least one pair (two if you can afford them or find them on sale) of the newest, most stylish shoes of the season," she says. "It's such an easy way to pick up on a trend and feel suddenly `in.'"

*Eyewear is another accessory not to be ignored.

"I don't think haircuts should dictate what frames you wear," she says. "It's all a matter of what you like when you turn to the mirror. And if you are forced to wear reading glasses, don't shy away from the old grandmother chain. Adorned with tortoise-shell links, beads, leather and bright stones, these chains have become quite a chic solution to keeping your glasses handy."

*Even if you're retired, don't retire the rest of your body. Halbreich believes in treating yourself to services like facials, massages, manicures and pedicures as "the ultimate treats."

But the one thing she feels is "truly a necessity" is a good haircut. "It's a huge plus to re-evaluate your hairstyle at least once a year, especially if you are going through a transitional stage in your life."

*The most important thing is to have fun with our wardrobes no matter what our age, says Halbreich. "We're all shoppers, whether we admit it or not," she says.

"Sure, there's a practical side to clothing yourself, but what keeps it going — why stores stay in business and designers keep on designing — is that fashion is also a whole lot of fun."