(FORTUNE Small Business) – It was once de rigueur for a business with aspirations to coolness to dispatch an army of teenaged cool hunters to discover the next big thing. Sadly, once the in thing was found, it was often already out. Now there is a new, more dependable approach, according to Tina Wells, the 24-year-old CEO of Buzz Marketing, who says companies are best off bringing teens inside their business as consultants. There are more than 33 million 12- to 19-year-old Americans, who last year spent $175 billion, according to Illinois-based Teenage Research Unlimited. And their economic impact goes beyond dollars doled out. "Teens influence their parents, who want to remain cool, as well as their younger siblings, who want to be just like them," says Wells. Buzz Marketing uses a network of 9,000 teens to help companies strategize about how to make a product, or a company, cool from the get-go. Here are three small businesses that Wells says are smartly applying these emerging teen-tactics. — JULIA BOORSTIN

TONY + TINA COSMETICS The seven-year-old, twentysomething-focused brand with $6 million in annual revenues wanted to grow its teen market.

TACTIC: Target influentials. The Manhattan-based company selected 50 popular high school girls, who each interact with at least 100 kids a day, to wear and talk about their makeup. These "influentials" are the well-connected 10% of the population that leads teen trends. After three weeks, traffic on the company's website shot up 25%, and the lip gloss the teens wore became Tony + Tina's top seller.

ZAZZLE.COM Launched in June 2003, the website allows customers to design T-shirts, posters, and cards for themselves or to sell on the site's online marketplace.

TACTIC: Extreme customization. >Teens want their purchases to be a do-it-yourself experience. Which is why Zazzle co-founder Matt Wilsey attempted to make the products as customizable as possible, allowing users to design every aspect of the shirts and posters they buy. "Independence-seeking teenagers are especially resistant to the cookie-cutter looks and products big companies sell," says Wilsey, whose company is based in Palo Alto. In its first year, Zazzle.com's revenues ballooned to $10 million.

HIP-E Kent Savage's son said he wanted an iMac. So the CEO of Digital Lifestyles Group, a company that sells PCs, consulted with 100 teens to design a PC that looked just as stylish as the Apple product.

TACTIC: Experiential marketing. Savage learned that you can't tell teens what to buy; they like to "discover" it for themselves. The CEO sent prototypes on Ashlee Simpson's 26-mall tour and left the computers, called Hip-e's, in mall kiosks for kids to try. It worked: Before the computer shipped in November, the website had more than 1.5 million hits and a steady stream of advance sales.