First, a cautionary tale: In the age of twenty, I flew from Sydney, Australia to Saigon, Vietnam Using a layover in Singapore. Caught up in the excitement, I failed to find out more about the travel visa requirements for all Americans. Turns out I needed to learn this lesson the hard way...

After almost an whole day of airplanes and airports, I came in Vietnam, sans visa. Within five minutes I was sent back to Singapore on the exact same plane. Fortunately, Singapore does not need a visa for Americans, and that I planned on flying back there anyways. Still, it took me eight years before I managed to go to Vietnam again...

Here is some hard won information for traveling visa conditions:

This point was driven home when I arrived in Vietnam. Many countries will allow you to buy a travel visa within their borders, but some don't. My advice would be to purchase them ahead, just in case. Besides, it is going to save you time when crossing the border.

Understand different visas available. One of my former customers was disallowed entrance into Brazil for company functions. After hours on the telephone with the embassy, we discovered that he could enter a tourist visa, and save a lot of headaches.

Keep a Zen-like calm. Let's be honest here: there's no place in the world that is more bureaucratic than a border; you receive the joy of dealing with not just one government, but 2 (like your own). Do not be surprised when there are surcharges,"handling fees" and time constraints... do your homework and prepare yourself ahead of time to prevent at least some of these delays.