Avoid receiving or giving somthing (business card, money...) with one hand
Why
Koreans find it very rude to receive something with one hand. Receiving with both hands at the same time or with one hand holding the other, is a great sign of respect.
Respect is deeply in their culture, so, avoid giving or receiving something with one hand to not offend anyone.
Alternative
If you give something with one hand, use your other hand to touch your elbow. Imagine the weight of what you are giving is so heavy that you need both hands.
Just do the same when you are receiving something, or accept it with two hands if you have a doubt.