I love traveling, & since I'm not a millionaire, I try to focus on getting the cheapest bang for my buck while I'm on the road. My three biggest expenses are accommodation, transportation & tours. I already talked about getting cheap accommodation. Now let's talk about transportation
For flights, I haven't found any website better than Kayak.com. I can search a dozen travel sites, but Kayak always comes up with the cheapest price. Always.
Many people believe that, within a country, domestic train or bus travel is cheaper than flying, & sometimes it is. But often a flight will cost the same as - or even less than - those slow modes of transportation. Case in point: I just checked online for travel between Sydney & Melbourne. Bus: $172, 10 hours. Plane: $52, an hour & a half.
It used to be that driving was one of the cheapest ways to go. No more. If you think the price of gas is high in the US, you should see the prices abroad. Here in Sydney, gas is $1.55 AUD per liter. That's $6.44 USD a gallon! If I wanted to drive from Sydney to Perth, it would cost about $650 USD in gas alone - one way - not to mention the daily cost of a rental car. To fly? $179.
It probably goes without saying that you should fly economy class wherever you go. Splurging on business class is nice if it's your annual two-week vacation, but if you're traveling for an extended period of time, the money you save by flying in the back of the bus could buy you a tour of some ancient ruins or a river rafting trip.
As with anything, weigh your options. Would you rather be pampered on a plane, or spend that money to do something amazing? The most important thing to remember when trying to stretch your dollar is to lower your standards. Don't be fussy about the frills & you'll be able to travel for a lot longer on the same amount of money.