Remember, even if they greet you in english, always speak slowly, clearly, and loudly and ask them this question before saying anything else:
DO... YOU... SPEAK... ENGLISH...???
If anyone speaks in a different language near you (even if it's not to you) turn to them and ask,
WHAT ... DID... YOU ...SAY? DO... YOU... SPEAK... ENGLISH...???
And, unlike in the US, it is actually appreciated when you clip your toenails at the table after dinner, to pass the time. It's ok to use your teeth only if you gesture wildly and talk loudly until they understand that you don't have your clippers with you.
-Adam