Marissa Mayer has been a pioneer in the unofficial "Geek is Chic" movement. Google's (GOOG) first female engineer, who is now the company's VP in charge of all things local, has appeared in Vogue, rocked the cover of Fortune's 40-Under-40 issue, and been nominated for Vanity Fair's 2011 International Best Dressed List. She is an angel investor in female-founded companies like Minted and One King's Lane. Mayer also mentors rising-star women through the Fortune/U.S. State Department international mentoring program -- and even has her mentees stay under her roof.

    Sometimes her extracurriculars drown out the recognition that Mayer, who is 36 and the youngest star ever on Fortune's Most Powerful Women list, knows precisely how to get ahead. Sure, she's been lucky. But she is also clever and strategic. On Tuesday, in a funny and candid interview at Fortune's Most Powerful Women dinner in Silicon Valley, Mayer explained how she does it.

Sometimes you just need to show up.

    Mayer found herself in an odd and maybe fateful situation when Tim and Nina Zagat, the famous restaurant raters, popped up at two conferences where she was speaking -- and sat before her in the front row. The first time they met, Tim walked up to Mayer, handed her his business card, and gruffly said, 'Welcome to local."

    Shortly after, in New York, the Zagats were in the audience again, front and center. And this time, Tim asked her to join his wine club.

    "I think that the Zagats are conference-stalking me," thought Mayer, who took control of the flirtation by asking Nina Zagat to lunch. Mayer was warned by Google M&A exec Neeraj Arora: "Don't say the acquisition word." But on the day they dined at New York's Jean-Georges (Nina's pricey suggestion) and continued their conversation at Zagat's Columbus Circle offices, Mayer couldn't help herself. She blurted: "Well, we're here to talk to you, maybe, possibly, about an… acquisition,"

    Actually, her directness worked. Google wanted to avoid a bidding war -- and the Zagats agreed to talk exclusively to Google over the months that they got to know each other. "There are times when you just have to show up," says Mayer, who learned this simple truth as the negotiations hit the final stage. Google left Zagat with a proposed deal on a Friday, to be finalized Monday. The talks could have taken place over the phone, but Mayer believed in-person was best. So she and her team did two red-eyes in four days. "Nina said, 'That was our litmus test,'" recalls Mayer. "They were like, 'Is this a good team to work with? How much of a personal connection do they want with us? If they come back, we want to be with [them].'"

    In September, Google acquired Zagat -- an ideal fit, Mayer believes, given Google's focus on local, mobile and social offerings.

Surround yourself with the smartest people possible.

    Mayer graduated from Stanford in 1999, amidst the height of the first tech bubble, when she had a good problem on her hands: 14 job offers. What to do?

    She says she looked for the common thread of all the best decisions she had made: going to Stanford, changing her major from pediatric neuroscience to symbolic systems, spending a summer working in artificial intelligence and another in banking in Zurich.

    "I always surrounded myself with the smartest people I could find," she say. She settled on Google, she adds, because she knew the team there would help her coding skills grow a lot, regardless of the startup's success.

Do something you're a little unready to do.

    Moving from Wisconsin to California for college and then changing her focus to symbolic systems --"a major I couldn't really describe myself, let alone to my father"--Mayer proved to herself that she could do things before she felt ready. Her biggest test, she says, came during her summer in Switzerland while she was a student at Stanford.

    And her A-ha moment came while shopping for food, of all things. "The first day, I went to the grocery store and got in trouble because, it turns out, you buy produce in Europe completely differently [than in America]." Mayer simply wanted to buy grapes (a fruit she so loved as a kid that her family nicknamed her "The Grape Ape"), but she couldn't master the process of weighing the fruit and printing the price sticker.

    "This woman just started yelling at me in German," Mayer recalls. The moment may seem trivial, but "I remember going back to my apartment and just being like, 'What was I thinking? I don't speak the language, I can't even buy produce here."

    "When you do something you're not ready to do, that's when you push yourself and you grow," she says she now realizes. "It's when you sort of move through that moment of discomfort of, 'Wow, what have I gotten myself into this time?'"

    Fortune's Pattie Sellers closed the interview with Mayer by reminding the audience of wisdom that Ginni Rometty, IBM's (IBM) new CEO, shared at the Most Powerful Women Summit in October: "Growth and comfort do not co-exist." Mayer would surely agree.