If I have seen the person for the first time. I say Hi and start a conversation by asking simple questions. If the person is a foreigner, I ask something like, " Where are you from?" and How is the weather in your city?"
If the person is someone I know and I haven't seen them for a while, I will ask the following questions.
1. How have you been?
2. I remember the last time I saw you were _____So, how are you now?
I also try to give a compliment, especially if it is a woman.
-- ' You look very pretty today."
--Your makeup looks great on you.
I tend to initiate a conversation, although it starts with a HELLO..You can vary your greetings.