It can vary depending on situation. Hello (mr/Miss/Mrs).... It could be hi or hey....one might just say what time of day like morning (name), or afternoon....

Depending on the setting and how well two people know each other it can vary greatly. For example if you are going into a business meeting it might be "Hello Mrs/Mr/Ms (Person's name)" or "Thank you for taking time to see me (Mrs/Mr/Ms (Person's name)". If two people already know each other it could range from a simple "hi" to some form of slang or their name.

I most often say, "Hi, how are you?"

I usually greet my friends in the US with: Hey (their name) What's up? How's it going? How have you been? - if i haven't seen someone in awhile

In formal settings, you often use a time-of-day greeting (not sure what they're called). In the morning when you first see the person, "good morning". For afternoon (past 12:00), "good afternoon"; evening or when you are leaving work around 5 or 6, "good evening". For very late engagements, when you are leaving home you might tell a friend, 'good evening' (when the most likely thing the person will do after seeing you is go to bed). This also applies to when you're at home when you are about to go to bed, you would say this to family members just before you head to your room and turn out the light.