Get casual: Loosen up your look—but only so far.

In today's workplace, every day has become Casual Friday. To me, it's not such a good thing. Some looks are not office appropriate for women of any age. They include super-low-riding jeans, ripped jeans, shoulder-baring halter dresses, midriff-baring tops, breast-baring camisoles, tight message T-shirts, microminis, hot pants, and flip-flops (the office is not the beach). But now that this clothing has become the new norm for people who work in "creative fields," you can see how a skirt and matching jacket, stockings, and pumps immediately look dated. "Dress less finished, and you'll look younger," says Sharyn Soleimani, personal shopper extraordinaire at Barneys New York. "When you're very young, you can be very finished and you still look young. But when you're more mature, imperfection looks so much better." If you're going to a casual dinner party at a friend's home on a Saturday night in the summer, a suit is too much. Ditch the skirt and wear the jacket (or better, a cardigan) with white jeans and strappy sandals. The goal is appropriately casual. Once you unleash yourself from the suit-as-uniform way of dressing, you will feel liberated and look 10 years (or more) younger.

Excerpted from How Not to Look Old: Fast and Effortless Ways to Look 10 Years Younger, 10 Pounds Lighter, 10 Times Better by Charla Krupp. Copyright © 2008 by Charla Krupp and the Stonesong Press, LLC. Published with permission of Grand Central Publishing. All rights reserved.

Dress fashionably, but don't be a fashion victim.

There's a big difference between being a slave to the latest trends and being aware of them. You want the latter. Every season, the fashion industry presents hundreds of trends. Some are exciting, some are fun, some are silly, and some are downright idiotic. Your mission is to be a smart shopper and buy only the trends that work for you—your body, your personality, your lifestyle.

Fashion coach Susan Sommers, whose business, Dresszing, helps women shop in their closets, advises her clients to ask themselves, "What one or two pieces will make my wardrobe pop right now?" The pieces don't have to be superexpensive, but they should be of the moment and the color and style should mix well with at least two items you already own. If the of-the-moment item is pricey, before you splurge ask yourself, "Is this something I can wear after this season is over?" Treat your wardrobe as an art collection, and curate it with looks that are worth the investment because they go the distance. If you have doubts, skip it. Know that you can always add a hit of style with more disposable items, like costume jewelry and other fun, instant-gratification accessories.

Excerpted from How Not to Look Old: Fast and Effortless Ways to Look 10 Years Younger, 10 Pounds Lighter, 10 Times Better by Charla Krupp. Copyright © 2008 by Charla Krupp and the Stonesong Press, LLC. Published with permission of Grand Central Publishing. All rights reserved.

Learn to love classics—with a twist.

Dressing effortlessly chic makes great use of classic shapes—the tried-and-true basics that have been around forever. And to keep them from being, well, classically boring, make sure they have some kind of a twist. Maybe it's a cashmere cardigan without buttons. Maybe it's a V-neck in a fresh color. A trenchcoat in black patent leather, rather than the expected khaki. Jacqueline Kennedy Onassis, who was the picture of ageless chic throughout her life, seldom strayed from the classics: a basic cashmere turtleneck sweater, a pretty twinset, a black sheath dress, fitted tweed trousers, and designer pumps. The principle of simple, casual shapes in quality fabrics holds true for every occasion—even cocktail parties: The idea there is to find those items in dressier fabrics such as eyelet, silk, chiffon, brocade, or velvet.

Forgive me if I repeat myself, but I can't say this enough: No matter how classic the look, or how hot it may be, don't be tempted to wear anything that doesn't flatter you. The tunic, for example, is a classic shape that's in style right now, but if you're very petite, a long tunic can overwhelm you and make you look like a sack of potatoes. Which brings me to my most important shopping to-do…

Excerpted from How Not to Look Old: Fast and Effortless Ways to Look 10 Years Younger, 10 Pounds Lighter, 10 Times Better by Charla Krupp. Copyright © 2008 by Charla Krupp and the Stonesong Press, LLC. Published with permission of Grand Central Publishing. All rights reserved.

Don't buy it if you don't love it. And love it only if it flatters you.

It doesn't matter what big name is on the label. It doesn't matter how low the price. Does the piece make you look good? Thinner, younger, hipper? Does it make you feel powerful? That's what's important. The lesson here: Buy less, buy better, be picky. If you can walk away without getting a pang, do yourself a favor and walk away. You don't need another piece of clothing in your closet taking up valuable real estate.

Excerpted from How Not to Look Old: Fast and Effortless Ways to Look 10 Years Younger, 10 Pounds Lighter, 10 Times Better by Charla Krupp. Copyright © 2008 by Charla Krupp and the Stonesong Press, LLC. Published with permission of Grand Central Publishing. All rights reserved.

Dress young, but not teenage young.

It's fine to shop for fun accessories and costume jewelry at stores like Forever 21 and Claire's, but buying clothing from retailers that cater to juniors will only make you look like you're trying too hard to look young. There's a reason the prices are cheaper in the teen department: The fabrics are cheap. And cheap fabrics are never flattering, especially on women over 17. Many of the mistakes that grown women make fall into the category of revealing too much, as in baring your midriff (unless you're at the beach). It doesn't matter if you have six-pack abs or paid six figures for a tummy tuck, keep it hidden—it's not cute.

Styles you should avoid

Excerpted from How Not to Look Old: Fast and Effortless Ways to Look 10 Years Younger, 10 Pounds Lighter, 10 Times Better by Charla Krupp. Copyright © 2008 by Charla Krupp and the Stonesong Press, LLC. Published with permission of Grand Central Publishing. All rights reserved.