German greetings and most common phrases :

guten Morgen = good morning
guten Tag = good day
hallo = hello
grüß Gott = good day (it means "God bless you" and is used in Austria and southern Germany)
guten Abend = good evening
gute Nacht = good night
auf Wiedersehen = goodbye (means "to see again")
tschüss = goodbye (in the informal language)

bitte = please
danke = thank you