Fashion expert Tim Gunn reveals what women over 40 should never wear.

Since the hit reality series Project Runway premiered on Bravo in 2004, Tim Gunn has delighted millions as mentor to the show's dueling designers. Although he's best known for his compassionate criticism and signature catchphrases, Tim is no stranger to the industry. He's been working in fashion for more than 20 years.

When the cameras are off, Tim serves as fashion chair at Parsons The New School for Design in New York City. He visits The Oprah Show to share the six things that no woman over 40 should ever wear.

Although it's not a long list, Tim says it's an important one. Women in their 40s should always try to avoid horizontal stripes, jackets that hit at mid-thigh, pleated pants, double-breasted blazers, Capri-length pants and low-rise jeans.
Makeup artist Bobbi Brown shares tips for older women.

Since the launch of her first line of lipsticks in 1991, makeup artist Bobbi Brown has been creating palettes and powders that flatter women of all ages. Now, as Bobbi prepares to turn 50, she's less concerned about concealing her age and more focused on celebrating her maturity.

"I'm so happy," she says. "I'm ready to be who I am. I'm ready to be the best I can be."

Bobbi says the key to looking beautiful at her age isn't what she puts on her face—it's how she cares for her body. "It's about [how you're] eating," she says. "It's about exercise more than anything else."

Skincare is also key for older women, she says. Remember that as you age, your skin gets drier. When this happens, Bobbi suggests that women switch from powder blush to cream rouge.
Kim, before her makeover

The Oprah Show tracked down five women who were stuck in a style rut and turned them over to Tim, Bobbi, hairstylist Ken Paves and colorist Rita Hazan, who all agreed to help these ladies revamp their looks.

First up is Kim, an elementary school lunch lady and mother of twins. Kim says she spends just 15 minutes a day getting ready for work and wears her hair in a bun almost every day. For years, she says she's been telling people that she's in her 40s so they think she looks good for her age.

Kim is actually 39.
Kim, after her makeover

Once Tim got Kim out of the lunchroom, he says she really gravitated toward this Milly geometric printed dress, which gives her a '60s mod look.

Then, Tim put Kim in black Christian Louboutin pumps to accentuate her gorgeous legs. "This is chic sophisticated," he tells Kim. "There's sexiness, [but] it's not remotely vulgar."

Chloe Holguin, creative director at the Ken Paves Salon in Beverly Hills, says they cut Kim's hair to elongate her neck and expose her jawline. Rita Hazan, owner of the Rita Hazan Salon in New York City, added highlights to create multidimensional color and brighten Kim's face.

Tim says the whole idea behind these makeovers is to show women their true potential. "It's really about discovering what was there to begin with," he says. "We're helping to pull it out and accentuate it."
Cindy, before her makeover

Cindy, a 44-year-old mom, says she hasn't changed her look in almost a decade. Not only are her clothes from last century, so is her hairstyle. She admits that she's been sporting the same French hair roll since the '90s. Plus, she sleeps in her makeup every night.

"What are your pores saying to you?" Oprah asks.

Tim thinks it's time for the real Cindy to shine through her foundation. "I saw you yesterday without any makeup, and you looked fabulous," he tells her. "[You're] naturally gorgeous."
Cindy, after her makeover

Tim's first goal is to tone down Cindy's look. "We wanted to make Cindy very believable and more a member of the real world, as opposed to looking like she's always going to a party," he says.

Dressed in an Ellen Tracy suede blazer, a Dana Buchman shell top, Ellen Tracy denim jeans and Manolo Blahnik pumps, Cindy looks like a modern woman!

Next, Bobbi revamps Cindy's makeup routine. "She was wearing so much eyeliner, we didn't see her eyes," Bobbi says.

In the salon, Ken and his stylists got rid of the French hair roll and gave Cindy a cut that flatters her fine features. Rita also softened her hair color by three shades.
Hillary, before her makeover

Call fashion 911! Hillary's a 53-year-old doctor who's suffering from severe frumpiness. Most days, Hillary says she wears her hair in a ponytail and thinks of herself as a plain Jane. Her wardrobe is also outdated…she even wears socks that she had in high school!

For years, Hillary says her friends have been begging her to try out a new look. Can Oprah's style experts resuscitate her fashion sense?
Hillary, after her makeover

Oprah's style experts breathe new life into Hillary's basic look. Tim helps Hillary choose a Diane von Furstenberg wrap dress and a pair of Manolo Blahnik pumps. "We took the classic black dress that every lady should have in her wardrobe and did this wonderful, high-spirited innovation of it," he says.

To complete the look, Rita warmed up Hillary's hair color with caramel highlights, and Bobbi used concealer to hide the darkness under Hillary's eyes.

Now, Tim says Hillary could pass for her teenage daughter!
Marlene, before her makeover

Over the years, Marlene, a 53-year-old mom and grandmother, says she feels like she lost some of her spark. Now, she's ready to embrace an exciting new style.

For women like Marlene, it's never too late to try something different. "It's so fantastic that we're celebrating maturity and experience," Tim says.
Marlene, after her makeover

To create the proper proportion, Tim put Marlene in a classic Lafayette 148 blazer that stops right at the hip bone. Underneath, she wears an Elie Tahari shell and an Etro silk bubble top. Marlene's Elie Tahari pants and Jil Sander shoes add just a touch of elegance.

The most dramatic transformation took place in the salon, where Rita took 20 years off Marlene's look by getting rid of the gray and adding chestnut color to her hair. "The first thing you see in a woman's face is her hair color," Rita says. "People skimp out on their hair color, and it's the most important thing."

Bobbi accentuates Marlene's blue eyes with a cobalt gel liner, and gives her skin a youthful glow with Extra SPF 25 Moisturizing Balm and Sand Pink Blush.
Sheila, before her makeover

Tim has seen almost everything during his time on Project Runway, but he's probably never met a woman like Sheila, a 38-year-old who calls herself "scrunchie girl."

Sheila is a jeans and T-shirt kind of girl who curls her bangs under like a jelly roll. Oprah says she used to wear her bangs like that…in high school!
Sheila, after her makeover

When Oprah sees Sheila's new look, she says, "No scrunchie munchy anymore!"

Wearing a Theory trench coat, a Rebecca Taylor dress and Michael Kors suede boots, Sheila looks years younger. Tim says this outfit is both stylish and versatile. "She could go day into evening quite simply," he says.

Gone are the scrunchies and the jelly roll bangs. Ken showed Sheila how getting her bangs off her face made her look more youthful. Then, Rita gave her hair a warm honey-blonde color to complete the look.

Bobbi says she evened out Sheila's skin with a yellow-toned foundation. "Makeup foundation should look like skin," she says. "It shouldn't look like foundation."