Forget any semblance of good manners - get those elbows out, brothers and sisters, and be prepared to push, jostle and even shoulder charge. Otherwise you risk not making it on to any public transport, to the front of any queues, or even getting fed at a café. It's not rude, it's just the way it is.
If you don't have a smartphone, get one, and download the best Mandarin translation app you can find. The Chinese grasp of English is tenuous, and that phone will be your lifeline, especially in taxis.
If you're travelling internally on Spring Airlines, don't bother taking a book - halfway through your flight the stewards perform a very entertaining exercise routine that all passengers dutifully follow, sort of like armchair aerobics. Only in China.
Carry your passport everywhere - we couldn't even rent bicycles in Shanghai without surrendering our passports: nothing else except a bucketload of cash would satisfy the rigid man at the rental joint that we weren't going to make off with his crappy mountain bikes.