So you have two weeks vacation time that you have to use. Schedule your time off regardless of whether you have a ticket or not and prepare for an adventure. As the time of your vacation draws near, start checking with travel agents for last-minute flight deals. Those prices you see in the windows of travel agencies are usually for flights departing within a week or two, and the seats are being sold off at better prices. If you book a flight in advance you have the benefit of being able to plan for a hotel and to research the country you are visiting, but you miss the great last-minute seat sales. Some of these flights are for fixed-length tickets and only have a one- or two-week validity.
Research airlines for the continent you are flying to. For example, if you're planning a trip to Asia, you'll have access to dozens of low-cost carries that don't fly to North America. Find out which airlines use which cities for their hub, then research flights to that city. For example, you can get to Bangkok via Seoul and Kuala Lumpur, using one airline to fly to Seoul then a discount airline to KL and onward. The total cost of the three flights, including taxes, may be less than a single ticket to your destination. In addition, you can spend as much or as little time in the routing cities as you like, as opposed to buying a ticket from one airline, which may not allow for stopovers at all. This way, you get three countries for the price of one.
Travel companies online have an uncanny ability to find incredibly cheap seats. It's often cheaper to book through an online travel agent than to book directly with an airline. If you've got a specific destination in mind, this can be the best way to get there. Some travel companies have weekly online specials, so check back regularly to see what's cheapest.
The culmination of all this advice is simple: be adventurous. A lot of exciting and interesting travel doesn't require a lot of advanced planning, as tour agents exist in every major city in the world and planning your itinerary on the fly can be thrilling. You can always buy a guide book at the airport's bookstore. The only planning you need to do is to check visa requirements for countries you may travel to, or you'll be turned around at the airport. Consider, finally, just packing a bag and heading to the airport one day. Set a budget for a ticket, then ask at the ticketing counters for last-minute or standby seats. The agents at the airport might be authorized to offer the absolute lowest prices in favor of sending a full plane to -- somewhere. Embrace the adventure!