-Do Your Homework-
Know what the actual exchange rate is. Just check out some finance news sites to see what the current rate is between Yen and Dollars or Pesos and Pounds. It only takes a few minutes to check and know for sure, and this will let you know whether or not the people you're checking out are actually giving you a fair rate or not. Obviously you're going to have to pay a little extra for the exchange fee and everything, but you need to know what you should be able to expect to pay just to make sure you don't pay too much more.
-Shop Around-
Look at everyone's rates, don't just settle for the first people you find. Look everywhere, make them compete for your business. This way you can find the lowest rates and get the most money back for your travel money purchase. It's a competitive market so make sure you take advantage of that and make them compete for your business. Check out everyone, not just the first two companies you can find.
-Use the Internet-
This one kind of goes without saying, doesn't it? You want to look at all the competition, and the only way to do that is to shop online, isn't it? With the internet, the entire world of the market is open to you, whereas in person you're restricted to just the places in your area. Shopping online can almost always guarantee you a better deal. This is just sort of a rule when it comes to the Twenty First Century. The internet just plain makes everything easier, from shopping around for great exchange rates to shopping online for rare items. The web opens the whole industry up to you and allows you to take your pick of everything available. So if you want a good rate, just use the internet and you're already half way there and can ensure that your trip overseas goes off without a hitch.
Tom is a writer for a range of travel publications. He recommends FairFX - http://www.fairfx.com/ - for the best deal on foriegn currency when going abroad.