Compare apples to apples

Some sites include extra fees up front, while others, such as Expedia, are sneaky and bundle up a vague compilation of taxes and service charges at the last minute. Booking policies can also be different--one site may penalize you $10 for canceling a hotel reservation, while at another there's no charge.

Book direct

Not only will you almost always pay less, chances are you'll get better treatment if you skip the third-party booking engines and make reservations directly. After our magazine mentioned a hotel executive who admitted that her company routinely gives the worst rooms in the house to customers who book through third-party sites, we received dozens of letters from readers saying that they'd been treated poorly at hotels for that very reason. "This is one family that will never use Travelocity again," a typical message read. Always remember that you're not done shopping around until you inquire directly at the source.

Consider opaque sites

They're nothing new, but sites such as Priceline and Hotwire--you don't find out which hotel, airline, or car-rental company you're working with until your bid has been accepted and your credit card charged--remain good money savers.

If you're looking in particular for a decent room for cheap in a big city, Priceline is a fine source. Check out Biddingfortravel.com, a kind of user's guide to Priceline, for help, but be aware that you may not be treated as well at the hotel as someone who's booked direct (see above).

Clean your cookies

Travel sites are engineered to get the most money out of users, sometimes by trickery. Kelly Malasics, of Bridgeport, Conn., wrote to us about her experience locating a great online fare to Las Vegas, only to have it disappear later in the day. "I deleted the cookies for the site and tried again," she said. "Voilà! I found the flight I wanted at the price I wanted." 

Pick up a phone

The old standard still works. Consolidator airline tickets, charter flights, and other unconventional resources that a good travel agent would know about can rarely be booked online. A hotel manager will be more willing to negotiate rates with a human voice than with a message on a computer screen. And it's often easier to talk through your options with a car-rental agent than scroll through them in the fine print online.