Greetings and common everyday expressions
Good Morning- Ohayo Gozaimasu.
good afternoon- Konnichi wa
good evening- Kon-ban wa.
Good Night- Oyasumi nasai
see you again-Mata Omeni kakaimasho(orMata oaishimasho)
see you tomorrow-myonichi omeni kakarimasu(or myonichi oai shimasho)
see you later- Nochihodo omeni kakarimasho
see uou soon- chikaiuchi ni omeni kakarimasu
Good-bye and good luck- syonara odaiji ni.
please take care of yourself- Dozo okarada o taisetsu(or odaiji) ni.
good luck and safe return- doka ogenki de ittekite kudasai(or gobuki ni)
we will pray for your success- goseiko o oinorishite orimasu
please give my thanks- okusan nimo yoroshiku
please give my love to your mother and everyone at home (i really don't think you'll use this one much but hey)- okasan ohajime mina-sama ni yoroshiku.
well, i earnestly desire your continuing good health- dewa kurefuremo okarada otaisetsu(or odaiji) ni