Unless you are planning a short domestic trip, the cost of airfare is usually a deciding factor in an overseas trip. Most people with moderate incomes simply can't afford to fly regularly, as much as they would like to. There are, however, some people out there who are flying all the time on regular incomes. The secret to achieving this is a willingness to be flexible and shop around with airfares, as well as employing some tried and true discount travel techniques.
The key to getting a cheap flight is to shop around, and the internet makes this easy for almost anyone to do. There are a plethora of websites that will conduct searches around the world for cheap airfares. Although the internet is a valuable tool in discovering cheap airfares, it's important that you don't rely on it entirely. Many sites claim they are searching "all flights" for the cheapest possible fare, but you really don't have any way of knowing what they do and don't have access to. Oftentimes the cheapest flights can come from the airlines themselves, and you'd be well advised to check their sites as well in your search.
No matter how much research you do online, you should always visit some travel agents. Keep in mind that these people make their livings selling airfares, and will often have access to deals that aren't available to you online. Think of it this way: if you really could always get the cheapest flight online, travel agents would be out of business. The fact that they are not suggests that good deals are to found the old fashioned way: by visiting the office of a travel agent.
When looking for discount travel, you should also explore non-traditional methods of finding flights. Websites like http://priceline.com offer reverse auction systems, that is: you place a bid of what you're willing to pay on a given route on a given date, and if it turns out that an airline is willing to release a seat for that price, your credit card is billed an a ticket is issued.
Another good avenue to explore is "bucket shops" - companies who buy bulk tickets from airlines at a heavy discount. They don't have the choice that travel agent has, of course, but if you're flexible you can often get a good deal. A typical bucket shop system will work as follows: you give them a week-long window during which you'd like to fly and some destination choices, and then if something comes up at the last minute you can have it at a heavy discount.
Another rarely explored discount travel technique is to look into bucket shops and travel agents located in ethnic neighborhoods. Often, foreign airlines sell discounted tickets to these shops, which in turn serve an ethnic community regularly traveling to their home country. These shops have access to tickets from airlines that often aren't available at your regular travel agent, and can offer a significant savings.
The important thing to remember in terms of discount travel is to explore as many avenues as you can. The more flexible you are willing to be, the cheaper your fare is likely to be - but even if you're stuck with rigid dates, a compressive search will often result in airfares that are significantly lower than those commonly advertised.