Do not use rickshaws/pedicabs/bicycle taxis. No traveler reported an honest experience. Australian couple was quoted "three", which they thought would be Yuan, but turned out to be 300, each! Their rickshaw unloaded them in a shady side street where they were fearful of arguing. I was pestered to take a pedicab about 2 miles to the club district, quoted 20 by the woman driver on her cell phone, responded with 10 fingers, to which she agreed, but upon arrival she wanted 20 US Dollars. I paid her 30 Yuan, double what an air-conditioned, faster, much safer metered automobile taxi would have cost, and she still yelled and screamed at me for 5 minutes.
Do not use a 100 Yuan note to pay a wandering vendor for a 15 Yuan t-shirt, watch, purse, etc. The change will be fake. Pay the exact amount. I met a German senior tourist given Belarussian 20 notes in change. Same size and color.
There are some fake 100s in circulation. Never take a 100 from a wandering vendor, or be helpful and provide change.
Taxis are in general honest, quick, air-conditioned, and cheap. Both yellow cabs and the red ones charge the same. Insist on the meter. It begins with a welcome announcement in English, and finishes with a thank you announcement in English and a receipt. Nobody tips. If a cab insists on negotiating a rate, they are dishonest, and might be dangerous and steal from you. Traffic can be horrible–that is not the driver's fault. 30 Yuan or 4 dollars will take you across town. The summer palace to the closest subway station is less than 50 Yuan. Marco Polo bridge to the Military Museum was about 35. Railway station to workers stadium nightclub district was 15 or 20 Yuan. Many taxis have a cage between the driver and passengers.
Don't pay too much. The fake Rolex watches can be had for 20 Yuan (I heard two travelers who bought their watches for just 10 Yuan), even though the salesman started at 150 Yuan (or in the case of an older, wealthier tourist 500 Yuan asking price!). Fake Prada purses can be had for as little as 50, maybe cheaper, starting price was 500. T-shirts on the Great Wall asked 150 and came down to 25 before I walked away.
Subway system is excellent. Clean, fast, well-marked. Cost is just 3 yuan. A local map of the neighborhood is in each station, but mostly in Chinese. The place to stand in line is marked. I never heard any problem about pickpockets on the subway. Beggars (lepers, deformed, handicapped) sometimes come on board, but are not aggressive.
The organized tours to the Badaling sector of the Great Wall are crap. The typical tour starts at 8 at your hotel, arrives about 10 at the first jade shop for a half hour, then after a 30 minute visit to a Ming tomb goes to a second jade shop for another half hour, then spends an hour at a bland lunch spot which is also a souvenir shop, and finally arrives in the heat of the day about 2:15 p.m. for the visit to the wall, with the bus returning starting at 4 p.m. About 6:20 p.m. you arrive at a tea shop for a formal tea ceremony, and only get back to the hotel about 7:30 p.m. Quality of the English and the commentary was poor. Bus could not use air conditioning for part of the congested trip. Our tour did not go to the Chang tomb, as advertised, but instead to another, lesser tomb. I would suggest to either go to another sector, or to take public transport or a taxi to Badaling in the morning when it is cooler.
Students, interns and workers who were staying many months in China reported the local water supply was safe throughout the country, maybe tastes a little of chloride.
Legitimate massage is cheap. Places like Pavilion near Guomao, and Baodhi behind Olive restaurant on the north side of Workers Stadium were recommended. About $25 for an hour.
Strangers, mostly student age, will approach on the street and practice their English. Sometimes they have motives to sell you art, or a visit to a tea shop, or ask you to buy them a drink. I am told Shanghai is worse.
Public toilets are fairly plentiful and reasonably clean.