你好 [Nǐ hǎo] should only be used as a polite greeting when meeting someone for the first time. When talking with friends or acquaintances, it should be replaced with another form of greeting instead:
嘿 (hēi, hey)/嗨 (hāi, hi)
Used amongst young people.
你去哪里? (Nǐ qù nǎlǐ? Where are you going?)
你去干吗? (Nǐ qù ɡànmá? What are you going to do?)
你吃了吗? (Nǐ chī le ma? Have you eaten yet?) Often used by older generations or in rural areas.
Head nod, waving, saying their name - no formal spoken greeting required
Amongst people who are already familiar with other, such as coworkers or close friends.
你好吗？ (Nǐ hǎo ma?)
Native Chinese speakers NEVER use this phrase. Instead they would simply ask:
How someone has been recently
If they haven’t seen each other for a long time.
More specific questions such as how your weekend went, how work was etc.
When greeting someone they’re already familiar with.
"Tā" = He? She? It?!?
他 (tā, he)/她 (tā, she)/它 (tā, it)
The pronouns "he", "she" and "it" are all pronounced "tā" in Chinese. There’s no way of telling them apart in oral Chinese without any extra information or seeing the written character form for clarification.
Saying goodbye to "再见 (zàijiàn)"
"再见 (zàijiàn)" should only be used when saying goodbye to people we are not particularly close with or when addressing someone we respect, as it is a fairly formal greeting. When talking to other close friends or colleagues, we can say these instead:
拜拜 (báibái, bye-bye) Mainly used among young people.
慢走 (màn zǒu, walk slowly/take it easy)
Often used by older generations or in rural areas.
我走啦！ (Wǒ zǒu la! I’m heading off!)
Can be said when you are the one who’s doing the leaving.