Guangzhou is a relatively safe destination, but foreign travelers are always susceptible to petty crimes. Pick-pockets and purse-snatchers are actually pretty common, so use good sense at all times, by locking valuables in the hotel safe, leaving jewelry at home, carrying limited amounts of cash, and storing that in a money belt. Also avoid walking around alone at night, especially in and around the train station. The good news is that serious crimes against foreigners are rare, partly due to the fact that the penalties are quite severe—including execution.

In terms of health risks, protect yourself from stomach upset by passing on the local water, ice, and produce, as well as any uncooked foods or unpasteurized dairy products. Stick to bottled water, and consider bringing an antidiarrheal medication with you from home just in case, since the quality of drugs in China is often questionable. Many travelers also return home with pneumonia or influenza, so consider getting an inoculation before you go.

Finally, ensure a pleasant visit by respecting the local traditions as much as possible, and refraining from voicing opinions contrary to China’s laws and customs.

Be aware of the amount of air pollution throughout Guangzhou. It is not always a blue sky. In order to protect yourself from the air pollution you can do one of two things. First, if you are staying for a long time,  recommend you get an air purifier. If not, stay in on extremely polluted days.

The subway is fairly new and modern, but excessively crowded especially on weekends and during rush hour time.  Also, the subway stations are crowded and stuffy during heavy peak times, and often so unorganized and signage could be better too.  Subway exits tend to be not well lighted at the street level,so be careful.  However, the subway stations inside are surprisingly clean and bright, with lots of shops at the more popular places.

If you are in trouble, dont' always expect your fellow man to help, and police stations are hard to find, and even so, maybe the police are busy with more "important" things.  So, don't walk alone at night, anywhere, because there are plenty of non-locals roaming the streets too.

Also, be very careful with making deals with local merchants.  Always remember that most are only interested in making money, so be sure to bargin or walk away, there are plenty of other stores.  Be aware of fakes of everything from eggs, milk, shampoo, even X5's, jade, everything can be bought fake.  Also, merchants come and go, so it's easy to loose your money because they just "disappear".