How do you hello in Austria?

There are many different ways to do so, depending on the situation: In formal situations you might say "Grüß Gott" or "Guten Tag", with "Guten Tag" being more common in Germany and bigger Austrian cities. In the morning a "Guten Morgen!" is the normal greeting, in the evening you might also say "Guten Abend", but that's not so commonly used. Between friends and family you also say "Guten Morgen" or just "Morgen" in the morning, for the rest of the day you can use a simple "Hallo" or "Hi" (rather city-ish) or "Grüß dich" (more countryside-ish)