Understanding Discount Fares.  You should understand about fares and how they can be legitimately cheaper. Many travel agency sites and, of course, online and print travel guides will explain how you can get cheaper rates for just about any aspect of travel.  For example, buying a consolidator air ticket with a credit card from a reputable travel agent is a very safe bet. (Consolidators buy a certain number of seats on specific flights directly from a scheduled airline at a wholesale price and then resell them to the public or to a travel agency who in turn resells them to you.) On the other hand, that promotion for 7-days in Hawaii for $110 is a much more risky proposition. If it is too good to be true, it probably is!

An Airfare Strategy.  This is for people who do not travel much or who are planning that big trip. Use several of the major on-line travel agency fare finder features to get a feel for the price range of your planned trip.  Shop around for the lowest fare and convenience (such as departure and arrival times and a direct flight)  Armed with fares from different airlines, you are in a better position to shop the net or work with a travel agent. Shop on or off the web.  If you can't find a really better deal, then go back to one of the original on-web sites and order the tickets on-line from them.  It shows them that you appreciate their making available to you the information you needed to make an informed decision. For international travel, especially out-of-the way places and if you will be an independent travel, it is becoming easier to book everything on line with your credit card not matter where in the world you are going. But you still need to do your research. 
  
Discount Travel Explained.  Here are two good sites that explain discount travel.

Fodor's Air Travel Information.  These people are well-known for their good travel information. Here you can see a list of articles and reader inputs related to air travel from their Travel Forum and Travel Wire sections. 
 
Smarter Living- Air Travel Topic.  They are one of the best travel sites on the web.  They offer a lot of advice and information on travel in general. We drop you off at their site search results for air travel where you will find a good list of recent articles or use their search box to find a specific topic. 
 

Of course, all on-line Travel Agencies search multiple airlines, but they do not always search all airlines or include consolidator fares. 

CheapFlights  A very nice interface based on departure/destination pairs only and not flight specific flight dates. The list will show cheap fares from various sources and the dates they are valid. You click on the link to the specific booking site to actually pick specific dates and book your flight. Note that some low fares listed are actually fares to nearby airports which you discover once you are on the booking page.

Lowestravel  They are one of the best website to find the lowest international airfares.

Mobissimo  They are one of the best website to book international travel.

FareReport  Select  a departure and destination city and it will show you the average one-way fare over the last year, the airline with the largest share and the airline with the lowest fare. It has a link to Booking Buddy so you can compare current airfares for your city pair as well as a link to a Priceline air travel window at tyzo.com.
 
BetterBidding  This site has, by far, the best list and access to the most consolidator companies.
 
ETN - Discount Airfare Worldwide Online  This site has, by far, the best list and access to the most consolidator and discount air fares of anyone on the web with excellent international coverage.  They also cover discounts for cruises, car rentals, and hotels.  Click here to go to their home page. 
 
WebFlyer  They are the Web's Frequent Flyer authority and true to their name they cover everything a frequent flyer wants to know. They are also a good source of the latest information on discounts being offered to any traveler by the airlines.