Ten expressions to greet people:
3. How's it going?
4. How do you do?
5. How's tricks?
7. How are things?
8. Haven't seen you for ages.
9. Great to see you again.
10. Nice to meet you.
How to use these phrases:
4 and 10 are quite formal. We use them when we meet someone for the first time.
The most general greeting is 2, which you can use in formal and informal situations, in business and with friends.
3, 5 and 7 are informal expressions you can use with friends or people you work with on a regular basis. 6 is very informal and is only used with good friends or people in informal situations.
8 and 9 can be used in informal situations when your last meeting was a long time ago.
The normal reply for all of them is: Fine. But with 1, 2 and 4 we repeat the same greeting.