Pheromones, nature's sniffable love potion #9, provide us with important information about compatibility. Though aftershave or cologne can mask a man's pheromones, a recent study showed that people tend to pick perfumes similar to their body's natural odor.

"Perfumes enhance one's own scent and, thus, entice members of the opposite sex," says biological psychologist Dr. Nick Neave of England's Northumbria University. So if you like a man's cologne, it could be a sign that you're compatible -- at least biologically.

According to Michael Marinoff, a bartender at New York's Maritime Hotel, the modern Casanova wears many disguises. "Players have become much more subtle," he says. "It's all about fusion."

If a guy looks like he's trying to merge many styles (e.g. a Brooks Brothers shirt with the sleeves ripped off), he could be attempting to multiply his options.

We can absorb as many as 10,000 nonverbal cues in less than a minute, says body language expert Patti Wood, and can form impressions in as little as one-fortieth of a second with an accuracy rate of up to 80 percent. So, check him out.

An overly broad stance could mean he's domineering. Are his feet pointing toward you? As Wood says, "Where the feet go, the heart follows." The timing of a smile is revealing, too. If he smiles before he speaks, he feels good about you; if his grin follows his speech, he could be faking it.

For the women of the 78th Police Precinct of New York City, spotting a shady character comes down to "Gut feeling, with both men and perps." Signals of sketchiness include lack of eye contact and fidgeting.

If his eyes roam over your body instead of resting on your face, you can probably guess his motives. And if he changes his gait or begins to perspire profusely upon spotting a cop, watch out -- "Oh, do they sweat."

Deborah Gunther, who practices the ancient Chinese art of facial reading, says there are countless ways to gauge a person's character through his face. A mouth full of curves is a sign of a sense of humor. Watch out for large, round nostrils, which could mean he can't hold onto money, or a jaw that is wider than his forehead, which signals a dictatorial personality. Thin lips can point to emotional repression, while fuller lips signal sensuality; and if you can see the inside of his lip when his mouth is closed, he may be promiscuous.

Our reaction to a man's voice is often instinctive and immediate. According to Sam Chwat, director of New York Speech Improvement Services, the response is primal: "Humans react differently to an animal that whimpers than to an animal that roars."

Nevertheless, Chwat notes, though one might interpret a soft voice as a sign of timidity, it could signal a willingness to listen. Similarly, an overly strident, forceful delivery might be his way of compensating for insecurity -- there could be a tiny mouse hidden inside that great big lion!

The doorman at New York's Four Seasons Hotel is a longtime observer of the wealthy -- and those who wish they were. His wisdom: "If a man is too interested in flash, his money is probably poorly managed." According to his colleague up the street, at the Pierre, "The watch tells you everything." Don't forget to check out his feet: The doormen concur that brown shoes paired with a blue suit equal a bad tip.

"Everyone is born psychic," says Tina Vlado at The Village Psychic in New York. "Some just more than others." Those of us less preternaturally inclined simply have to focus.

"When you first meet someone," Vlado suggests, "stop for a second, breathe, and get a sense of the energy." Strong, silent types are usually easier to read. "When they're talking too much, it's almost like they're hiding something," she says.

Adele Testani, the cofounder of HurryDate, is candid about first impressions. "You're not going to be able to tell if you want to marry him," she says. "But you can tell a lot about humor, attraction, and chemistry."

In a speed-dating scenario, nerves run high. So pay less attention to what he's saying -- "My name is Harry, I enjoy sushi and Trivial Pursuit" -- than to which topics end up dominating his time. You'll learn more about his values while taking into account the limits of the situation.