Giving and receiving is a matter of pride, respect and honor in Korean culture. This said there are certain rules that must be applied. While we as Americans are given latitude to disregard said rules, I think it is best to assimilate as much as possible.
When giving and receiving, it is best to do it with both hands (palms up). Especially if you are receiving from someone who is older or in some other way has a higher status than you. When students receive anything from me such as a worksheet or candy as a reward they should always receive it with both hands. Because they are the students and I am the teacher there is a very clear level of respect that should be adhered to.
This rule transcends to nearly every situation. For example: When I pay for a candy bar at the local convenience store, the cashier will most often receive the money from me with both hands. I, in return, should hand the money over with both hands. This can be very cumbersome but nuances of the rule allows for a little help. While juggling gloves, a wallet and my new purchase it isn't always convenient to hand money over with both hands. It is acceptable to hand the item with the right hand and touch the forearm lightly with the left hand. Somehow, the little forearm touching gesture indicates giving with both hands.
This rule is very important at the dinner table as you should never pour your own drink, but instead offer to pour drinks for others. When pouring, it is best to pour with both hands on the bottle and the person receiving picks up the glass and receives with both hands. It is quite common to trade pouring responsibilities throughout the meal.