Guten Tag! (Good day!) This can be said till 4:00 p.m.
Guten Abend! (Good evening!) This can be said till late in the night.
Gute Nacht! (Good night!) Said before you go to bed or when you are parting from someone late at night.
Remember to say Guten Morgen and not just Morgen. Morgen means morning. But what we want to do is to hope that the person has a good morning.
Similarly, in English, never say just "Morning!" Instead, we have to say Good Morning!
Wie geht es Ihnen? (How are you?)
Danke, gut. Und Ihnen? (Fine, thank you. And you?)
When someone asks you how are you are, it is imperative for you to ask them how they are. This is a formality that must be maintained. This is a question that is popped so that you can start a friendly conversation.
Auf Weidersehen! (Good bye!)
Auf Wiedersehen! (Good bye!)
On the phone, one says: Auf Wiederhören!
Other ways of saying goodbye in German are:
Tschüss, Tschö, Tschau, Ciao(These are more informal)
Tips:
1. It is important to say these phrases in a friendly manner and with a smile on your face.
2. Study your face in the mirror. Ask yourself whether it is a friendly face. People could get irritated with a handsome or beautiful face when there is no warmth and smile on the face. So remember, your smile is your greatest asset. Make sure it is always there! A smile always comes back to you!