What can I do for you today?
How may I help you?
May I help you?
Can I be of any help?
Can I be at your service?
What do you do?
What do you do for a living?
A: Hey! Gina. How are things?
B: Great. Mr Jones. What can I do for you today?
A: I'm preparing for my first meet-and-greet tomorrow morning. Can you give me any advice?
B: Sure. First, as a famous writer, it's important that you greet people properly. If you're speaking to a businessman, I suggest saying, "Good morning, I'm Brendon Jones. How do you do?"
A: And what do I say to a teenager?
B: keep it casual. Something like: "Morning, what's happening?"
A: Shouldn't I say: "what's up?"
B: No! Definitely not, that's too casual. Only teenage friends would say that.
A: And what about someone I have met before? Should I say: "I haven't seen you in years?"
B: It's better to say: "what a pleasant surprise seeing you here".