Chinese Basic 1
First contact

Simple greetings and goodbyes

你好 (nǐ hǎo) hello (literally you well) is a common greeting that can be used pretty much anywhere and at any time.
您好 (nín hǎo), how do you do is a more formal greeting used to express special respect for the addressee. It is typically used when meeting people more senior in age or status or when greeting customers. In such situations the reply is often simply 你好.
At a first meeting you will often hear 很高兴认识你/您 (hěn gāoxìng rènshi nǐ/nín) very happy to meet you.
The reply is often 我也很高兴认识你/您 . (Wǒ yě hěn gāoxìng rènshi nǐ/nín) I am also very happy to meet you.
The most common way to say goodbye is 再见 (zài jiàn) (literally again see).