It used to be all so simple, back when airfares changed so infrequently that airlines actually printed them on their schedules. You'd call your favorite travel agent to find the best deal, pack your bags, and jet off. And there were only two kinds of fares: coach and first class.

Now, with airfares changing literally by the second and an alphabet soup of different offers, finding the "best" deal is a challenge. But don't give up hope. This step-by-step guide will get you ready for takeoff.

Sign up for free airfare alerts 

Why do all the work hunting down a low airfare yourself when you can have someone else do it for free? Many airfare search and listing sites, such as TripAdvisor.com/flights, Travelocity.com, Farecompare.com, Hotwire.com, and Bing.com/travel (and, of course, Airfarewatchdog.com) offer e-mailed airfare alerts when prices go down. This chart compares many of the leading airfare alert sites. (By the way, only Airfarewatchdog lists fares on Southwest Airlines).

Get e-mail from your airlines 

Next: Sign up for e-mails and frequent flier programs. Airlines are trying to woo customers to book directly with them by offering special deals when you subscribe.  Here's where to sign up for emails from foreign-based airlines and here from U.S.-based carriers.

Next step: are you a flexible travel date flier? 

Doesn't really matter when you go as long as it's cheap? Some websites offer flexible date search up to 330 days ahead; others (mostly those powered by a company called ITASoftware) only do searches in 30-day increments.  Learn more about flexible date searches on major sites.

These sites can be helpful if your dates are set, but you also might want to try "meta search" sites such as Kayak.com, Tripadvisor.com/Flights, and Momondo.com.  Warning: None of them include Southwest's fares, however, or fares on the smaller but growing Allegiant Airlines.

"Meta search" vs. online travel agency (OTA) 

So what's the difference? For one thing, online travel agencies such as Expedia have toll-free numbers with agents standing by to help you book or re-book a flight; meta-search sites don't. But there are many other differences.

Airline websites sometimes have the best fares 

Increasingly, airlines aren't sharing their very best fares with third-party sites such as Kayak. Case in point: recent fares to London from the West Coast for $420 round-trip including tax that were only available on Spanish airline Iberia's website (similar fares were twice that elsewhere). So once you've found a fare, definitely check airline sites directly.

Watch out for promo codes 

From time to time, you'll receive promo codes in your e-mail because you signed up for e-mail from your favorite airlines and online travel agencies. These codes can only be redeemed if you book directly on the airlines' websites, another way they try to cut out the middleman.

When to use your miles 

Rather than cashing in 25,000 or even 50,000 miles for a domestic economy class ticket that might have cost you $250 or $300, why not splurge for a trip to Europe (50,000 miles on some airlines) that might cost many times more; or upgrade your $400 economy class seat to a $2,800 business class fare for 30,000 miles on domestic routes? A general rule: if the economy class fare is $400 or more, spending 25,000 miles is a good deal. Less than that, you might be better offering paying cash and saving your miles.

Getting the best last-minute airfares 

You'll often get the best fares if you book at least 7 to 21 days ahead of departure. Otherwise, your best bet is Priceline.com's "Name your own price" feature or Hotwire.com. Also take a look at Lastminute.com which packages last minute airfares with hotel and rental car deals—sometimes for less than what you'd pay for airfare alone.

When to use a real live travel agent 

As good as do-it-yourself online sources can be, your friendly neighborhood travel agent may have some tricks up her sleeve to save you money. Let's say, for example, that you get an airfare alert that fares from Houston to Honolulu are $800 round-trip. But who knew that the fare from Dallas to Honolulu, same dates, is going for just $300. Or that you can fly from Houston to Dallas for $100 and connect onward? A savvy travel agent.

Getting a refund when the fare drops after you buy 

Several domestic U.S. airlines will give you a full refund, in the form of a voucher good for future travel, if the airfare drops between the time you buy and time you fly—if and only if you fly on the same itinerary. Most foreign-based airlines won't however. Details here.

Watch out for fees 

A low fare on one airline could turn out to be not so low once fees are added on. Airlines are making most of their profits these days not from selling you airfares but with all those fees for baggage and other perks.  In addition to checked bag fees (see chart) there are even fees now for using your frequent flyer miles and other services such as changing a travel date or bringing a pet onboard.

Best days to travel 

Although a low airfare can pop up at any moment, one thing's for certain: it's cheaper to fly on a Tuesday or Wednesday. Saturday is also a low-fare day. If traveling internationally, Monday to Wednesday is often the sweet spot.

Is there a "magic" hour or day to buy? 

It's true that the airlines' weekend deals come out Monday to Wednesday, and some airlines announce their sales early in the week, but if you limit yourself to searching just on those days, you'll miss out. A good fare can pop up any moment of the week.  

Airfare predictions 

Speaking of "when to buy," Bing.com/travel purports to offer accurate airfare predictions, indicating whether the site thinks a fare will go up or down, and it's certainly worth a try, but it's not always accurate. To see if an airfare is currently on the high or low side, do a web search for "historic airfares" to see airfare trends on a particular route. Two useful sites: Farereport.com and Kayak.com/trends.

Also worth reading:

"Hidden City" fares can save money, but sometimes at great cost

Holiday airfare savings tips

Time to rethink what a "cheap" airfare is?

All products and services mentioned on Airfarewatchdog are independently selected by our team of expert travelers. If you buy something through our links, we may earn an affiliate commission.

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