Flash those beautiful teeth
The best advice I can offer is this: Learn how to laugh at yourself! This is huge. You will be in countless situations (geographically, linguistically, culturally) where you are not in charge, don't fully understand what's going on, are completely lost. You must retain a bomb-proof sense of humor. Try watching episodes of "The Daily Show" and see how John Stewart does it. Watch "Dumb and Dumber," "Blazing Saddles," whatever it takes to instill in you the fact that life is too short to always look cool, and that the only way to navigate life abroad is with your big, toothy, ever-ready smile.