These are all common ways of saying "hello" in English and some possible responses: -Hey ... Hi -What's up (wassup)? ... Nothing much, how bout you? -Hi ... Hey, are you good? -How's it going? ... Good, and you? -How are you? ... I'm doing great, how bout yourself? -Yo ... Wassup? Now these responses are not REQUIRED by any means, but they sound normal to me as a native speaker. Also here are some common goodbyes as well: -See ya, see ya later -Later -Peace out, peace -Bye

All those are good ones, but they do miss 'Hi' and 'Hiya'. you can respond to 'How are you?' and 'How's it going?' with 'Fine thx' because they're asking how you are. With 'What's new?' and 'What's going on?' you could just answer with 'nothing much' or just tell them what's been happening to you recently. Did that make any sense at all?

I like to use those: Sup?(what's up?) Howdy? You! Sounds more native for me.LOL