Culture

Superstitions:
Do avoid to use red ink, since red ink traditionally was used to convey an insulting message. Especially, do not write names in red ink - this symbolises death! As the word for the number '4' sounds like death in Korean, many buildings do not have a fourth floor.

Gifts:
When visiting a Korean friend's home, it is customary to bring a gift. The gift can be almost anything.
At first, your host may refuse it not to appear greedy. In this case, just insist your host accepts the gift, which will be appreciated. However, it is customary to open presents when the presenter is not present.
If you're so fortunate as to be invited to a wedding, do not bring a gift. Rather bring money in a small envelope with your name as well as a few congratulatory words like "Congratulations!" or "Happiness"

Gestures:
Although the western handshake is common, the proper way of greeting is with a bow. When giving or receiving, especially when drinking alcohol, always use both hands. Some gestures have a complety different meaning in Korea. You should be aware, that the symbol for "OK" (making a circle with your thumb and index finger) means "money" to Koreans.
Do not 'steal children's noses', as a thumb sticking out between the index finger and middle finger is an obscene gesture.

Manners:
As in other asian countries shoes must be removed before entering a room. However, many places such as restaurants and hotels have sections with western furniture - tables and chairs. If visiting a private home wear socks, since bare feet can be offensive to elderly people.
Leaving utencils stuck upright in a bowl of rice is bad manners, as this is a gesture used when making food offerings to ancestors.
It is very common to use a toothpick after a meal. When doing so, use both hands - one to cover your mouth and one to work the toothpick.
It is customary that one person pays for everyone when dining or drinking. The Koreans do NOT 'go dutch' on the bill. However, if the party goes different places it is not unusual, that a different person pays each place.
In places with many people, it is not unusual that Koreans will push you or bump into you. There is no reason to be offended, since no harm is intended and this is an acceptable behavior in Korea.

Tipping:
It is not popular to give tips in Korea, so there really aren't any guidelines for when and how much. Many restaurants and bars include a 'Service Charge' o 10% on the bill, which can be considered a tip.

from: http://ezmeditour.com/