Just remember that in every country you go to, a smile is considered polite.
Otherwise, I used a website that my school uses as a reference for students studying abroad. It's a very reliable site.
Gestures
"Proper courtesy is shown with gestures. Items are passed with both hands or the right hand grasped by the left at the wrist or forearm. Feet are not placed on a desk or chair. When yawning or using a toothpick, one covers the mouth. Koreans beckon by waving the fingers together with the palm down. Beckoning with the index finger is rude. Facial expressions are often more important than body language in communicating unspoken messages. When embarrassed, a person may respond by laughing. People may also laugh if they are uncertain of how to respond. Eye contact is important in conversation among peers, but a person may avoid eye contact in conversation with a person of a different age group."
Greetings
"A bow is the traditional greeting, but it is usually accompanied by a handshake between men. As a sign of respect, the left hand may support or rest under the right forearm during the handshake. Women shake hands less often than men do. Among friends and relatives, a simple nod is acceptable. Children bow when greeting adults. Professionals meeting for the first time exchange business cards, presenting and accepting the cards with both hands after a handshake."
Visiting:
"Guests invited to a home remove their shoes upon entering. While Western furniture is common, in many homes guests are seated on floor cushions. Men sit cross-legged and women tuck their legs to one side behind them. The guest receives the warmest or best position. When visiting relatives, men and women usually separate to socialize. For example, the women gather in the kitchen. Refreshments usually are served. Guests invited for a meal customarily bring a small gift, often something that can be served at the gathering. Wrapped gifts are not opened in front of the giver. At the end of a visit, the host accompanies the guests to the door or outside. "
Good luck in Korea! Have fun!