By learning the basics of polite conversation, you'll very quickly be able to interact with Korean-speakers on a simple level. Try learning the words/phrases for:
Hello = 안녕 pronounced "anyeaong" (in a casual way) and "anyeong-haseyo" in a formal way
Yes = 네 pronounced "ne" or "un"
No = 아니요 pronounced "ani" or "aniyo"
Thank you = 감사합니다 pronounced "kam-sa-ham-nee-da"
My name is... = 저는 ___ 입니다 pronounced "joneun ___ imnida"
How are you? = 어떠십니까? pronounced "otto-shim-nikka"
Pleased to meet you = 만나서 반가워요 pronounced "mannaso bangawo-yo" or "mannaso bangawo"
Goodbye = 안녕히 계세요 pronounced "an-nyounghi kye-sayo"