It's shortly after 11 a.m. on a Tuesday weighted by a bullet-grey sky. Willis Murphy, one beer and a rock of crack cocaine into the day, has nabbed a decent corner at the I-395 off-ramp at Northeast First Avenue in downtown Miami.

The traffic light flashes to red, and motorists stack up in a neat queue. Murphy shuffles along the macadam holding his penned cardboard sign: "HUNGRY AND BROKE - anything at all HELPS. GOD BLESS YOU!"

He ambles back with an empty palm.

Here, amid the rumble of traffic on the highway overhead and the plumes of exhaust from tractor-trailers lumbering to the port, is a corner of the economy so familiar that it is often overlooked. Dozens of such hard-luck hubs exist throughout South Florida as centers for the most basic of economic transactions -- begging.

Studies show most panhandlers are unemployed, unmarried men in their 30s and 40s with substance abuse problems, few family ties, a high-school education and laborers' skills. They are also entrepreneurs of sorts, driven by desperation rather than dreams.

It's hard to know just how much money goes to panhandling in South Florida. But about 8,000 people are homeless in Miami-Dade and Broward counties, and although not all panhandle, those who do earn an average of $20 to $30 a day. On the roughest of counts, that means the industry brings in around $16,000 a day.

The money comes from donations of $1 or less, and regulars can account for up to half of all receipts, says Michael Scott, a former Lauderhill police chief and panhandling expert who now heads the Center for Problem-Oriented Policing in Wisconsin.

Just like any other trade, panhandling has its own rules to maximize revenue.

Murphy, a 49-year-old Kentuckian with a crack habit spanning two decades, is an old hand at the handout game, although he says he feels embarrassed that he's doing it. "I used to hate panhandlers myself, " he says.

He's found a sign to be a reliable marketing tool. In terms of sympathy-getting techniques, it falls between the simple proffering of a cup and fancy props such as wheelchairs.

"People notice the sign, " Murphy says. "Some guys don't like them because the police see them, but it works. I tried crutches one time, but it took so long to walk down the line of cars and they hurt my arms. I threw them away."

PLAYING THE PART

You have to look the part, too. Don't smoke or drink on the job -- or get high. "People can tell from your eyes, " he says. "And if you're smoking, they'll think you have money for cigarettes."

He smiles sheepishly when the cloying scent of beer on his breath betrays a violation of the regs. "Yeah, I know, " he says.

Murphy makes another foray along the queue of stopped cars, trying to establish eye contact with the drivers and win some change.

He doesn't bother with the swanky Mercedes or BMWs -- their owners tend to be stingy. Regular folks are more generous. He returns with a plastic box of rice and ground meat -- a woman's given him her lunch. Lacking utensils, Murphy raises the container to his lips and slurps a mouthful of rice. Grains stick to his whiskers as he munches.

He'd rather have cash, of course, but he's glad to get food. "Sometimes being out here I miss the free meals at the shelters, " he explains.

WAITING ON LADY LUCK

Persistence is key. You never know when Lady Luck -- and she is often a lady -- will happen by.

"Twice in my life, I've been given a hundred-dollar bill, " he says. His face creases into a grin at the memory. "It's a little bit exciting -- you never know what someone's going to give."