(FORTUNE Magazine) – It's midnight in Moscow. At the entrance to the Up & Down Club, a black-bereted ex-paratrooper is exercising "face control," the two-way radio in his fist as firm a deterrent to trespass as any Kalishnikov. Keeping out the unworthy is a priority for elite establishments the world over, but in Moscow it is virtually a solemn duty. And therein lies a key cultural insight for any business traveler in Moscow: You'll never get anywhere here if you're not krutoi.

Krutoi literally means "steep." But when referring to the quality that gets you into Moscow's elite watering holes, the word translates better as "cool"--a state that's easier to recognize than it is to define, but has to do with exuding a general aura of riches and danger. And if you're looking to impress business prospects--or just looking to get in the door of the best nightspots--you would do well to cultivate it.

First, a few krutoi fundamentals:

--Attitude counts. What works in the U.S. can easily be misinterpreted over here. So for starters, wipe that smile off your face. Russians save their fabled personal warmth for insiders, thick-and-thin comrades they have thrown up with or otherwise verified under duress. For appropriate demeanor toward the world at large, try, as the expression goes, looking like the flat side of an iron. Next, toss those lessons in corporate democracy. Russian business is only gradually weaning itself from the dictum of the Soviet workplace: "I'm the boss; you're an idiot. You're the boss; I'm an idiot." Let them know who's boss.

--Don't go overboard. The kill-with-your-bare-hands look is declasse in today's Westernizing Moscow and downright taboo in the very best places. Nevertheless, looking as if you could order a murder over croissants in your Lake Como villa remains much in fashion.

--Vodka comes in grams or milliliters. A minimum social dose is 100 (3.2 oz., or two shots), barring a doctor's note that documents an actively bleeding ulcer. A $300 bottle of wine can get you off the hook sometimes. Mixed drinks are still for sissies.

--Money comes in cash. Few Americans noticed when the Treasury redesigned the hundred-dollar bill two years ago. In Russia there was panic. Yes, you can more or less do Moscow on plastic if you stick to a Michelin itinerary and get in before midnight--but a cash reserve can prove awfully useful.

Once you have absorbed the rules, you can move on to the more advanced courses in krutoi, which are conducted every evening in Moscow's top nightspots. To a knowledgeable student, each represents a distinct phase in the post-Soviet evolution of Moscow mores.

The Up & Down Club, which took the town by storm in 1994, represents the high-roller phase, when fortunes were gained and lost in a matter of months, often taking their owners with them. The premises, usually deserted until midnight, are a painstaking reproduction of a wee-hours Las Vegas dive, replete with a Wall of Fame featuring Michael Jackson's hat and a tuxedo Al Pacino wore in The Godfather. Upstairs are gaming tables and an extremely intimate striptease venue. Recent customers of note include Russia's most powerful banker, Vladimir Potanin, and U.N. Secretary-General Kofi Annan.

Club-T, which opened in late 1995, epitomizes the mock Georgian phase, when the high rollers began to travel to Geneva and make exaggerated stabs at a Continental grand manner. Late, intimate suppers from a Parisian chef are the forte here (and can run to $200 without drinks). A white grand piano tinkles soothingly in the small, candle-lit dining room. Customers are warned to wear ties and "express themselves in cultured language," says a manager who will identify himself only as Mikhail. The $1,500 bottles on the restaurant's list "sell well, though of course not every day," he adds modestly. Famous guests spotted: media magnate Vladimir Goussinsky and Communist Party chief Gennady Zyuganov.

A newer hot eatery, Bochka ("The Barrel"), offers a glimpse of the future--the Upper West Side phase. Well, sort of: The Friday night special, bull roasted on an open spit, might not draw much of a crowd on New York City's Columbus Avenue. But most other particulars match. The exposed-brick interior was once a garment factory. Severely coifed women sport no-nonsense office blazers. The drinks are Evian and designer beer, the chatter of internal politics at newspapers and ad agencies. Dinner is just conventionally overpriced at $50 to $70.

But the premier Moscow power spot of the moment is Tsarskaya Okhota ("The Tsar's Hunt"). Proprietor Arkady Novikov, who also owns Club-T, chose the location brilliantly: It's situated in a lodge in the pine woods out of town, just past the turnoff for Barvikha, Boris Yeltsin's country residence. (His daughters come to Tsarskaya Okhota; Yeltsin himself entertains at home.)

Inside, wolf skins cover the barstools. Venison leg (traditional Russian health food) is roasted before a massive hearth. Plates brim; vodka flows. You can limit yourself to the $50 smorgasbord--a literal wagonload of creamed and pickled delicacies, tilted heavily toward the beet and herring families--and the help will still smile at you. This is the Great Gatsby phase of Russian capitalism, as close as you can get without a time machine to the way Peter the Great kicked back.

Not surprisingly, Russians rarely do breakfast meetings. The workday starts at a civilized ten. Still, after a night at one of these places, being your usual powerful self by that hour may not be easy. If you can pull it off, well, then you really will be krutoi.