Learn some of the basic language so you can at least be able to have some communication with the locals. Introductions and pleasantries are always important to know but make sure you can communicate when it comes to money, passports and finding help in emergencies.
Always know the address and phone number of the closest embassy. Check with American Express to see if an office is close to where you are staying. They always speak English there and can help you with money concerns as well as current exchange rates.
Learn local customs and traditions of the country and city where you will be staying. We don't always realize that there are little things that we do that may be considered an insult in another country. For instance, a wink or wearing shoes indoors may be considered very offensive in some countries.