Common greetings, pleasantries in English

Saying hello.

Hello - formal
Hi - informal
Hey - very informal - you have met before
Heyya - very informal - you have met before
Hiya - very informal - you have met before
Hey man - very very informal, usually just for guys who are friends
Good to see you - Good ta see ya.
Nice to see you. - Nice ta see ya.
Nice to meet you. (Formal. First time meeting).
Pleased to meet you. (Formal. First time meeting).
Good morning.
Morning. (informal)
Good afternoon.
Good evening.
Long time, no see. (Informal - they haven't seen you for a while.)
Hey. It's been a while. (Informal - they haven't seen you for a while.)

RESPONSE: Hello. Hi. Yeah, it's been a while. Etc.

Asking how someone is, how is their work, etc.

How are you? (Formal)
How do you do? (VERY formal)
How are you doing? ** sounds like ** Howya doin?
How have you been? ** sounds like ** Howya bin?
How are things? ** sounds like ** How'r things?
How is everything? ** sounds like ** Howz everything?
How's it going? ** sounds like ** Howzit goin?
How's life? ** sounds like ** Howz life?
How's work? ** sounds like ** Howz work?
How's school? ** sounds like ** Howz school?

RESPONSE: Fine. Fine, thanks. Good. Great. Super. OK. Not bad.

Asking in other ways...

What's new? ** often sounds like ** S'new?
What's up? ** often sounds like ** S'up?
What's going on? ** sounds like ** What's goin on? OR S'goin on?
How is your day? ** sounds like ** Howz yer day?
How is your day going? ** sounds like ** Howz yer day goin?

RESPONSE: Not much. The usual. Same old, same old. Nothing new.

Saying good-bye

Good-bye!
Good night!
Bye!
Bye-bye!
See ya!
Later!
See you later! See ya later!
See you soon! Hope to see you again soon! See ya soon! Hope ta see ya again soon!

RESPONSE: Good-bye. Good night! Etc.