I just buy directly from the foreign airline’s website.
I first use orbitz.com to get a convenient matrix summary of the flight options from various airlines. I review the type of flights, types of connections, etc.
I suggest kayak.com, which searches multiple sites like priceline, orbitz, etc and gives you a list of all their results. I got a multi-destination flight to southeast asia for $1150 that way.
I’d add: once you’ve found an acceptable price for an acceptable route, check the airline’s website before you complete your order. I’ve done this and had the tickets turn up slightly cheaper when buying direct - not every time, but often enough to be worth a quick check.
I travel once or twice a year between Ohio and Australia. I try to travel on United, because it makes sense to build up the frequent flier miles by going with one airline, but the same tactic can be used for other airlines. I check on a general site like Orbitz or Travelocity to see what all the airlines are charging, and perhaps play around with dates a bit, especially if I’m close to a peak season, then book on United’s site.
(As an example of why playing around with dates can be important: I’m going to Australian in December this year, and returning on December 28th. Why that date? Well, I want to be with my family for Christmas, and checking on prices for a return around that time showed that for each day after December 28th, the return fare went up by about $100. And why is this a peak? Well, it’s not particularly for Americans: it’s all the Australians, who want to be be home at Christmas, then get January off, and so are flying off to spend January somewhere in North America. January is when schools get their long summer vacation in Australia, and some businesses close down then too.)