Compiling a list of the best travel secrets is trickier than you'd think. For starters, the very act of publishing them gives them away, which is why I limited myself to those "secrets" that will be just as useful and effective after they're exposed. Second, what constitutes "best"? Those that are least known? most improve the travel experience? help the greatest number of travelers? In the end, I opted for the secrets that have garnered me the most thank-yous from Condé Nast Traveler readers over the years. Voilà:

1. How do you get the lowest airfare?
Itasoftware.com provides the most comprehensive and least biased list of fare and route options. Find out which airline offers the best itinerary for the lowest price, then go to that carrier's Web site to book. Itasoftware does not list flights on foreign low-cost airlines, however, so to find out which fly where, use whichbudget.com or wegolo.com.

2. How do you get the best seat in coach?
Before accepting an airline seat assignment, go to seatguru.com and look up the aircraft you're flying. Seatguru will tell you which seats offer extra leg or elbow room and which to avoid—such as those that don't recline, have immovable armrests, or have an obstructed view of the movie screen.

3. How can you snag mileage-award seats to your destination?
Lo and behold, there is someone who can help: LaDonna Epler, who used to work for the now-defunct awardplanner.com, knows the tricks and strategies for redeeming miles to get you where you want to go—by, say, flying on partner airlines or alternate routes you haven't thought of. E-mail her at ladonna.epler@yahoo.com. Another option: Call the carrier you have your miles with immediately after midnight in the time zone where it has its U.S. headquarters. Typically, award reservations expire if they're not ticketed by midnight, so you can possibly nab the seats that someone else has just forfeited.

4. Which credit card allows you to collect the most miles you can actually use?
The Starwood AmEx card lets you redeem your miles on any of 30 airlines (including every major U.S. carrier) and earns you the equivalent of 1.25 miles per dollar spent: AmEx gives you one point per dollar, but when you redeem points for miles, Starwood throws in an extra 5,000 points for each 20,000 you redeem.

5. What's the easiest way to earn miles?
Do your online shopping via airline Web sites. Continental, Delta, and other carriers link their sites to an enormous range of stores—such as Lands' End, Staples, and Barnes & Noble—where you can earn up to ten miles per dollar spent.

6. Which are the best days to fly for a long weekend?
Taking two days off work? You'll find cheaper fares and greater seat availability if you fly on a Saturday and return on a Tuesday, instead of going from Thursday to Sunday or Friday to Monday.