1. Be Prepared
Always carry tissues with you. This is mainly for when you have to use a public toilet. In Asia the majority of toilets will not provide toilet paper. They also come in handy at other times, wet wipes might be useful too especially if you like street food.
2. Cash is King
As I have mentioned in a previous post, China is a big fan of cash. Make sure that you arrive in China with some Rénmínbì and don't assume that you will be able to use your bank cards. Bank of China and HSBC ATM's are your best bet for making withdrawals.
3. The Language Barrier
Language is probably the biggest barrier you will encounter. Do not assume that there will be people who can speak English, they more than likely won't. Don't rely on body language either, even 1-10 are different here when counting on your fingers.
Try and familiarise yourself with some Chinese characters before you leave and it's helpful to make a note of any hotel addresses in characters in case you get a taxi/get lost. Most hotels have business cards at reception that you can pick up once there. Learning to speak a few words in Mandarin wouldn't hurt either.
4. Beware of the dreaded Mao's Revenge!
It is common knowledge that the first six weeks of being in China are the harshest on your stomach. This is due to a combination of different types of foods, eating times, foreign bacteria and hygiene (or lack of).
With that in mind, bring hand sanitizer, eat from busy food stalls/carts that are cooking fresh, hot food, and avoid drinking tap water unless you boil it for 20 minutes first.
5. Travel with an Open Mind
China is a unique country with a lot to offer but cultural and social norms are different to home. This can at times be a bit shocking, but this shouldn't put you off. It is all part of experiencing another country and culture.