Chinese culture is dissimilar to our own in some ways you might not expect.
For a start, the Chinese do not place such a high value on personal privacy as we do. That doesn't mean that when you arrive in Beijing you'll be put in a hotel room with ten other people, but it does mean you'll notice the Chinese are significantly different when it comes to personal interactions than westerners. They have, for example, a much less highly-developed sense of personal space than we do - so a complete stranger who was unaware of western habits might stand literally inches away if you're talking.
There is also no taboo against staring, which can seem very odd to first-time visitors. If you're particularly western looking (blonde, say) and you're outside of the coastal super cities and major tourist areas, you may find people staring right at you in the street. Again, this is related to Chinese's culture's lower valuation of the individual self. Someone staring at you probably isn't being hostile, just curious. It can be a little weird at first, but it's not something you're going to notice as much in Beijing or Shanghai.
You'll also notice that the Chinese are loud! This may seem odd at first, as this is a culture that values civility and good manners. But a bunch of Chinese talking to each other on a subway train (and they do talk to each other - this isn't London or New York where everyone lives in their own little bubble) can be truly deafening. Listening to Chinese languages is fascinating, though. The word "languages" is used carefully, there, because in truth there is more than one Chinese language. All are related to each other, but often they are mutually unintelligible. The really interesting thing is that the Chinese written language is the same everywhere, but because a Mandarin speaker (say) can say the words completely differently from a Cantonese speaker (say), difficulties can arise. However, two Chinese who appear to speak completely different languages can communicate with each other easily in writing.
Mandarin is the most important Chinese language, spoken by a majority of the population and used as the official language of business and government. It's a pretty tough language to learn, as unlike English and most other western European languages it relies on tones rather, rather than simply ordered syllables, to convey meaning - hence some of the quite nasal noises you'll hear when two Chinese talk to one another.