Goodbye is super similar to Hello in Korean also.
This makes it easy to get started. The only confusing bit is there are two that sound very similar, and the meanings are likewise.
μλ ν κ°μΈμ (annyeonghi gaseyo). This means goodbye and is used when you are staying, but the other person is leaving.
However, when you are leavingβ¦
μλ ν κ³μΈμ (annyeonghi gyeseyo).
Very subtle difference 
However, I learnt a new one on my trip to Seoul which isβ¦
μ κ°μ (jal gayo) - it means go well and reminds me of ζ ’θ΅° in Chinese which is used very commonly in Mainland China. It can only be used when someone else is going, not you though.
I like to use this one 