Write out your itinerary in as much detail as possible, making sure, at minimum, to list all major cities with international airports you plan to visit. As international arrival and departure taxes can vary extensively between airports, even those which are close together, it's a good idea to have a number of options open if you want to limit your exposure to these taxes.
Compare departure and arrival taxes for all the airports on your list online. Price flights to each destination, paying close attention to the amount listed in the "Taxes and Fees" section. For instance, if you're planning a trip to the Middle East from New York you might price flights to Amman, Jordan, Cairo, Egypt and Beirut, Lebanon if you plan to visit all three of those cities at some point during your journey. The airline you use is not important because the taxes and fees will be the same for all the airlines at a given airport. Price round trip flights as one-way flights in each direction to see the difference between departure and arrival taxes. A list of flight search tools is available in the "Resources" section.
Compare the amount you can save on taxes by traveling to a certain airport with how much you might spend getting from that airport to another destination. For example, if the difference in taxes between landing in Beirut rather than Cairo is $78, but a one-way flight from Beirut to Cairo is $100 more expensive than the other way around, it might not be worth it for you to exercise that option. Consider the large-scale costs of your trip and not just the initial tax savings you might enjoy.
Consider flying in and out of different airports. In addition to the fact that departure taxes can vary as widely as arrival taxes, completing your journey without having to return to another city can save you the expense of buying a ticket back to your origin, getting a hotel and so forth. Imagine, for example, after having chose to fly into Amman, you find that Cairo airport levies a departure tax of $11, while Amman airport's is $25. In addition to saving $14 per passenger by flying out of Cairo, you can save the cost of a return flight from Cairo to Amman. If you choose to do this, it's important to make sure the cost of two one-way flights - in this instance, New York-Amman and Cairo-New York, are cheaper than the roundtrip - New York-Amman-New York, for example.
