I have only officially worked in 3 different countries, but 5 if you count my short stint in Nespresso in Switzerland and African Outback in South Africa, so I am certainly not an expert. But what I have learned, I will share:
1. Pay attention when you are surprised at work
Whether you are pleasantly surprised or ending up feeling frustrated, pay attention to those feelings and analyze carefully what might be the root cause of that. As a foreigner, understand that the innate cultural differences can cause quite a shock to your system. It can certainly be your colleague's unique character, or it might be the common place thing for all natives to do, especially if you start to recognize a pattern. For me, after multiple frustrations, I realize that it was just a cultural response and there were no ill intentions what so ever. If you can't beat em, join'em!
2. There are multiple cultural aspects at play
As you start to dissect why certain situations arise, understand that the culture of the people, the company and individual personalities all come into the mix and they will interplay and leave you befuddled. From my experience, the culture of the natives is probably the strongest underlying factor and the individual personalities come a close second.
3. Let stereotypes be a way to develop relationships
Interactions with your colleagues will quickly help you understand how they see you and what kind of stereotypes they have about you. You will learn more about perceptions of your culture, but you will also learn how to dispel them gently. People are often proud of their "keen" observations and when the time is right, they will share them with you. (I had a boss where he was shocked I added milk in my coffee, he was pretty sure all Asians were lactose intolerant... really odd, but I was able to smooth things over by listening to his hypothesis and engaging in an interesting exchange)
4. Fit in when you need to, but stand out when you should
After learning more about the culture you are working in, leverage the fact that you can fit in when you want to, but really stand out when you should. You will be forgiven because you are different, but more often, you will be appreciated, for doing what's right and daring to break the cultural shackles.
5. Prepare yourself for "20 Questions"
When you work in a different country, people will inevitably ask about your culture and country. So be prepared and brush up on your history, political situation and any interesting nuggets of information! Especially if you are an American, because the pervasiveness of US media is so wide that your colleagues will no doubt already have an opinion about the US. If that's the case, refer to point #3.
There you have it, the top 5 things I learned when working in different cultures. What have you learned?