How do you say hi and bye?

"Hi" and "bye" are already greetings and farewells! However, here are some variations depending on context and formality:

Informal:

* Hi: Hey, Hello, What's up?, Sup?, Howdy

* Bye: See ya, Later, Catch ya later, Peace out, Take care

Formal:

* Hi: Good morning/afternoon/evening, Hello, Greetings

* Bye: Goodbye, Farewell, Have a good day/evening, Best wishes

Other options:

* Informal: Yo, What's going on?

* Formal: Good to see you, It was nice talking to you

Remember: The best way to greet someone is to choose a greeting that feels natural and comfortable for you and the situation.