How do native Chinese greet each other on daily basis? I have read somewhere that "你好" and "你好吗?" are mostly textbook greetings and are not used by native Chinese, at least not on daily basis. I would also find it hard to believe that two friends who know each other for years would still greet each other with 你好！:)

So, what do the Chinese use? For acquaintances? Friends? Relatives? Family? People you've just met? How much does the level of closeness with the other person determine the greeting?
This is a very interesting question. I am sure you can understand that even in English there are tons of ways to greet one single friend. It also differs from regions. Below I am listing some of the typical/common ways we greet people.


People you've just met: 


你好！＝ hello.  
很高兴认识你！ = very glad to meet you.

For acquaintances: 


你好吗？= how are you doing?  
忙吗？ = are you busy recently?  
最近忙什么？= what have you been up to recently?  
身体好吗？= Are you well/healthy?  
吃过饭了吗？= have you eaten? — This is very typical and old-fashioned Chinese way to greet. It has been used by the older generation more frequently. Chinese won't be surprised if they are greeted this way when the timing is not applicable. Seldom will they misunderstand this as a lunch/dinner invitation. It is just a greeting....) 

For close friends:  


嗨/嘿！hi/hey.
怎么样/你怎么样？= how are you doing?

For relatives: 

for close relatives, we don't even greet a lot. Just call "Mom/Dad". for relatives who we don't get to meet a lot, we use the similar greeting as acquaintances.