If you've been a traveler before, you're likely to be shocked that customs differ one culture to another. It's important to educate(you) on the rules of politeness in advance.
In Pakistan, if you go out for a meal eating with your right hand, the left hand is considered(clean). Don't show anyone the bottom of your shoes, and try not to touch others with either of your(foot).
In Russia, don't smile at strangers. That is a rude behavior;can make you seem impolite. When(pay) for goods, place your money on the counter (柜台) instead of handing it directly to the salesman.
In China, be generous with saying "thank you", if someone(do) anything good for you, such as pouring you tea, giving you a hand, and so on. And if you receivegift, take it with both hands.
In Korea, remember not(touch) a person while talking to him, and keep a proper distance: personal space is very important. Try to avoid talking too much during meals, and (active) offer to pay even if you know that someone is treating you.