When you book online, you're often on your own.

That's the message we hear again and again from fellow travelers: When the room that looked great online turned out to be a dump; when you mistakenly booked the rental car in your maiden name; when you booked a tour at a euro price when you thought it was dollars - you've got no one to blame except yourself.

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Linda Smith of Miami heeds that lesson. Though she's never been burned booking online, she's cautious. So when she found an unusually good deal on a New York City hotel room in March at an unfamiliar booking site, she snagged it. But she contacted us to find out how to check the validity of an Internet site.

A savvy consumer, Smith already had done what she could:

Carefully checked the booking rules, which allowed her to cancel without penalty until the day before check-in - a more liberal policy than what's allowed by some sites.

Checked for professional memberships: The site claimed membership in organizations including the American Society of Travel Agents, though she had trouble verifying the membership because the company does business under several names.

Checked with the Manhattan Better Business Bureau and found out that the company has a satisfactory rating.

Called the hotel and verified that they have her reservation.

Talked with her credit card company, which told her it would offer a credit if the room didn't exist at the last minute - even though the charge was initially made months earlier. (This isn't the case with all credit cards.)

"It's a terrible feeling - you could be in New York without a place to lay your head. Online, you don't know who you're dealing with," she says. "I won't know until March how it worked out."

Is the hassle worth it? For Smith, the answer is yes. She saved more than $125 per night.

About 68 million other leisure travelers agree. That's the number who booked this year via the Internet, for total sales of $104 billion, says Henry Harteveldt, vice president at Forrester Research, which tracks travel trends.

But the number of "bookers" - those who use the Internet to research and book trips - has dropped 9 percent since 2004, Harteveldt says. Spending increased $30.4 billion, or 41 percent, in that time, however, because bookers took more trips, he says.

Meanwhile, the number of "lookers" - travelers who research online but book elsewhere - has dropped in the last two years, while those who ignore the Internet for travel planning increased 50 percent this year, Harteveldt says.

The researcher attributes the declines to travelers' frustration with the industry, which he says needs to make the system more consumer-friendly.

Still, researching and shopping online has its benefits, such as being able to trade tips and evaluate options 24 hours a day, seven days a week.

Increasingly, technology is helping make it easier. Some sites - usually those set up by an airline or hotel - offer "talk back" options that allow shoppers to communicate with an agent in real time via the Internet.

Many have added e-mail newsletters and downloadable widgets that alert travelers to sales and price changes on trips that interest them most. On some sites, for instance, "you can say, 'Here's my budget,' and they'll let you know when a fare that meets your budget is available," Harteveldt says.

One of the biggest additions of recent years: traveler reviews.

Since launching in 2000, TripAdvisor has racked up more than 10 million hotel reviews from 5 million registered members. With more than 25 million unique monthly visitors, TripAdvisor rates as the world's largest travel community, spokesman Brooke Ferencsik says. Though hotel reviews are the site's best-known feature, user-generated photos, videos and "go lists" - individual travelers' favorites - are growing.

The drawback: At TripAdvisor, anyone can post a review, whether they've stayed at the hotel or not - and whether they're an experienced traveler or a novice.

Travel expert Pauline Frommer discovered the downside during a trip to Hawaii, when she visited a hotel for her Pauline Frommer's Guides that didn't match the glowing reviews on TripAdvisor. Frommer learned that the owner, after a negative review on the site, had encouraged friends and past guests to submit positive ones.

Hotel booking sites such as Quikbook, Expedia and Hotels.com also have added user reviews, but only travelers who have booked the hotel through their services can post opinions.

Qualified or not, such reviews can punch up business or smash it. Forrester's research indicates that 36 percent of travelers look at traveler ratings when choosing a hotel, and of those, 73 percent said the reviews affected their choice. Yet only 29 percent of travelers have written reviews, Harteveldt says.

Interactivity isn't just about reviews, message boards, and the sort of forums long popular on Lonely Planet and Cruise Critic.

Increasingly, the Web offers tools that enable travelers to get customized information for trip planning.

Mapping - offered by sites such as Mapquest, Google Maps, Rand McNally and AAA - has gone a step further with tools that pinpoint gas stations closest to the airport (Expedia) and stations to get cheap gas (Gasbuddy and Mapquest:

). AAA's Fuel Cost Calculator (

) will help figure out how much you're likely to spend on gas during a trip.

And if you're looking for fuel of another sort, Pubwalk maps pub itineraries in more than 65 U.S. cities.

As groups of friends and family have hit the road together, sites such as Triphub have become more popular, helping them discuss plans, plot an itinerary, and share maps.

Podcasts and mobile-enabled features are also growing. Cities including Philadelphia (

) offer free podcast tours, while sites such as Priceline allow travelers with mobile devices (such as phones and PDAs) to check real-time hotel availability, then call directly to someone who can book the room.

The most useful Web sites offer accurate, timely information that's easy to access. That can include:

Up-to-the-hour details on lines and delays at airports (Flightstats and Orbitz);

Forecasts of when airfares will likely be cheapest (Farecompare and Farecast);

The best and worst seats on various airplanes (Seatguru);

The price of winning bids on Priceline (

);

Alerts when airfares have dropped on tickets you've already bought (Yapta);

Locations of pet-friendly hotels (

» READ MORE: www.dogfriendly.com

);

Videos of hotel rooms in Europe (TVtrip).

So much information from so many sources may be overwhelming. One answer: Consult an expert.

Editorial publications such as Cruise Critic, Smarter Travel, World Hum, Hotel Chatter, and Professional Travel Guide, and newspapers, magazines and guidebooks offer unbiased expert opinions online.

Many feature timely blogs, such as Arthur Frommer's blog (

» READ MORE: www.frommers.com/blog

); TravelMavens (

» READ MORE: www.travelmavens.net

), run by David Molyneaux, the retired travel editor at the Cleveland Plain Dealer; and the Miami Herald's "Travels With Jane" and "An Insanely Busy Person's Guide to Getting the Vacation You Need," where travelers can post comments and ask questions.

And don't forget travel agents. No, they aren't extinct.

While few travelers these days will use an agent to book a simple air ticket to New York - an agent fee might run $50 - studies suggest that an increasing number of travelers are opting to shortcut the time-consuming Internet-booking process in favor of agents, especially for complex itineraries and luxury trips. And as many as 90 percent of cruises are still booked through agents.

Lang Baumgarten, a Miami real estate investor, says he would rather pay a service fee to his agent than spend his own time on the phone or Web.

"I think the Internet is a great tool, and if I hear about a new hotel, I'll go online and look it up," he says. But when it comes to booking, "I would prefer to delegate to someone who does something for a profession and really knows about it. I don't have the patience."

Recently, his agent was out of town, so Baumgarten called a hotel where he has often stayed. When the agent returned, he called the hotel and got Baumgarten a better rate and a hotel spending credit - earning Baumgarten more than the fee he'll pay the agent.

Assistant travel editor Bill Reed contributed to this article.