Koreans don't distinguish the greeting by the time like "good morning", "good afternoon". We just say "hi" as "안녕하세요. an-nyung-ha-se-yo." However, some may say "좋은 아침" as the direct translation of "good morning" because our language is influenced by western (american) culture.
Often "How are you?" is more stressed with various expressions in greeting. for example, "어떻게 지내세요?" "요즘 재미는 좋아요?" "잘 지내세요?" and so on...there are many expression for it.

You can say "행운을 빕니다 haeng-un-ul-bip-ni-da" for "good luck"

wish this is helpful for you. ^^