Quick. You're striding through a crowded airport on the way to your flight when the well-dressed woman in front of you suddenly drops her purse, spilling change and personal items all over the concourse. Should you stop to help pick up her belongings?

Not if means putting down your bag. She might be setting you up for what police call a distraction theft. While you're gallantly scooping up nickels and quarters, a confederate of hers -- or even a brazen opportunist passing by -- might walk off with your suitcase. Similar thefts happen in airports every day.

There were more than 2,000 crimes reported at Los Angeles International Airport last year, with theft the most common. From L.A. to Chicago to Rome, the tricks thieves use are almost always the same, preying on weary, distracted or even naively polite airport visitors.

The odds of sailing through an airport unscathed are definitely in your favor -- more than 67 million passengers passed through LAX in 2000 -- but the bad guys are out there, intent on ruining your next trip.

"They've been committing the same scams for centuries," said travel safety consultant Kevin Coffey. "They've just updated them during the past 10 years."

Thieves who commit travel crimes tend to fall into two categories. The first is made up of criminal opportunists, the everyday lowlifes travelers can usually spot.

"It's the guy we've all seen on 'Cops,'" says Coffey, a former airport detective, "the shifty character who doesn't fit."

The other, more dangerous type of crook is the travel specialist, who has developed an area of expertise and sticks to it as a career. Such scam artists do fit in, moving easily through airports disguised as business or leisure travelers. They may be men or women, often working in groups, executing carefully choreographed deceptions. One nervy thief at LAX stole mountains of luggage while dressed as an airline pilot.

Their preferred hunting grounds are large international airports, says Coffey, president of Calabasas, Calif.-based Corporate Travel Safety. Such airports have the most visitors, many of whom are jet-lagged, befuddled and don't speak the local language.

Crooks know travelers have business or leisure itineraries that beckon and are less likely to stick around and make a police report or look at mug shots of suspects. It's also less likely that they'll be willing to come back to town and testify should an arrest be made.

So what steps can you take to avoid being the victim of a travel scam?

Start planning before you leave home. If you intend to check your bag, don't put anything inside that you would be devastated to lose -- no family heirlooms, critical documents or heart medication. Pretend you will never see any of it again. Put critical items in your carry-on luggage.

Tape your name and contact information inside. If thieves don't yank off your luggage tags, they may disappear in the rough-and-tumble of an airport conveyor system. Without references, the airline or police may not be able to reunite you with your bags. Some travelers include a hotel itinerary so they can be located away from home. A few extremely thorough people actually carry itemized descriptions of the contents of their bags or take Polaroid photos of what they pack.

While the list of what missing items most airline will pay for is surprisingly short (forget about false teeth, musical instruments or airline tickets), your odds of being reimbursed improve if you can say exactly what was lost or stolen. And don't be surprised if you're asked to produce the receipt for that pinstripe suit you bought three years ago.

Mark your bag with tape or paint, anything that makes it more visible from a distance. Your property will be easier to spot in a crowd and less likely to be picked up by a crook or a mistaken honest traveler.

Lock your bags to help keep luggage handlers honest. There are also special locking straps or covers available in travel stores that can provide an extra layer of protection. Another effective measure is to tightly bind your bag in industrial-grade plastic wrap. If it arrives cut, you know you've had an unwelcome visitor en route.When you arrive at the airport, it's time to really start paying attention.

"Watch your hat and coat, as the old restaurant sign used to say," says Chief Bernard J. Wilson of the airport police at LAX. "It's not a crime-ridden place, but as is the case anywhere there are crowds, there are opportunities for people to take advantage of you."

Reported crime at the airport has been falling for the past four years, Wilson said. Passenger traffic continues to sharply increase, however, which heightens the challenge for law enforcement to further reduce crime statistics.