Now that Halloween is behind us, the official holiday season has begun. Soon store windows will be decorated with cardboard turkeys — and travelers will be packing their bags to visit family and friends all over the country.

But this year travelers had better book flights ahead of time. Airlines, still reeling under a weak economy and fears of terrorism, are limiting the number of airplanes flying in an effort to bring fares back to profitable levels. By cutting back on supply, airlines are hoping to fly with a full house during the holidays.

"Planes are flying more full than we've seen them in about 30 years," said Amy Bohutinksy, a consumer travel expert with Hotwire.com (search). "You're going to find that flights are going to be more expensive and more full as we get closer to the holidays."

The cheap, last-minute online fares of yesteryear are now tougher to find.

"If you see that good fare ... it's time to grab it. You may not see a better one," said Amy Ziff of Travelocity.com. "We're noticing that fares are rising an average of 5 to 8 percent higher than they were last year at this time."

Consumers can still surf specific hotel and airline Web sites, but mega-travel sites like Travelocity.com, Expedia.com and Orbitz.com are still where most of the bargains are to be found.

Ski destinations and beach trips are the two priciest vacations over the holidays and most deals are already booked. But if travelers are flexible on when they head for the slopes or the ocean, they can save up to 50 percent.

"Two of the most affordable weeks of the year to go somewhere warm or to ski are actually the first two weeks in December between the two peak holiday periods when people are staying home," Bohutinsky said.

Warm weather favorites in Fodors'  (search) recent survey of the top 20 hotels in the world include the Lodge at Ko'ele in Hawaii, the Montage Resort and Spa (search) in Laguna Beach, Calif., and the Corcovado Lodge Tent Camp in Costa Rica.

But for many people, holiday travel doesn't mean lounging in the sun or speeding down the slopes. It means heading to their hometown and reconnecting with family — and travel dates aren't very flexible. For those travelers, the best advice is to book flights as soon as possible.  

And wherever you plan travel, arrive two hours before for domestic flights and three hours early when traveling abroad to avoid dampening your holiday cheer.

Brenda Buttner currently serves as a senior business correspondent and host of "Bulls and Bears" (Saturdays 10-10:30 a.m. ET) on Fox News Channel (FNC). Based in New York, she joined the network in 2000.