There are different ways to greet people:

• “How do you do?” or “Pleased to meet you.”

“How do you do?” isn’t really a question, it just means “Hello”.

Greeting

• Hi, hello.
• How are you? How are you doing? How do you do?

Responding to greeting

• Hi, hello.
• I’m fine thank you (thanks)/Okay! Thank you (thanks)/Not bad.
• How about you?/And you?
• How do you do?