So I've been to China and it was weird, weird and awesome. There are some things that are totally different in China, and some I knew about, and some I had no idea about and had to learn the cumbersome way. I'm collecting these wisdoms here for you dear reader to benefit from.
* Chinese language and english: Chinese is built in a way that is very different from English. No bending of words, so nothing like greener or bigger. In Chinese it would be more green or more big. When I understood this it was easier to understand stuff. "I know" does not mean the same thing in Chinese, it means "Thank you for explaining, I understand now." Not what we might think as "Shut up, I know all this already."
* Food. All I met wanted me to know a lot about China and Chinese foods. Sometimes though, they order "local delicacies" that they wont eat themselves. While this might make a fun story back home I'm not ashamed for skipping a few delicacies that no-one else ate. Always drink water from bottles. Bīng means cold, learn this word. Exercise in front of the mirror your best impression of being cold. Otherwise you will have to drink everything lukewarm.
* Medicin: I had packed several packs of Dimor, a Loperamide that stops with diarrhea. I always had one on my person. One in my backpack. One in my suitcase and one in my toiletry case. Yes I needed to use it. I also packed all other medication I thought I would ever need.
* Internet. Internet in China sucked where I was. Everything is blocked in all of China. Get a VPN service before (if you have gmail or files in dropbox). Then get a backup VPN Service as well, maybe on one of your home computers. And then get a web surfing proxy installed on a web server somewhere
* Taxi. Taxis are scary, get a Uber app (there are several) and get those cabs instead. Much safer. Also, apparently there is no law that requires seatbelt in the backseats of cars. And you get looked at funny if you ask for it in a regular cab.
* Electric outlets. You don't need to worry about it. In the places I've been they have _all_ the standards. Worst case buy a power strip that extends to a lot of different devices. Everything I found was at around 220-230v.
* Toilets, you really need to know (at least in theory) how to use a squat toilet. I did not and apparently (after reading up on the internet) I now know that I used a very hilarious solution. HowTo Link
P.S. These advice are not everything you need. Normal stuff, like what is the difference in weather from where you are currently at and all that other stuff still applies.