Sao Paulo is known for a high crime rate and though Brazil’s largest city it isn’t known as one of its nicest or most touristy.
As long as you are able to take necessary precautions though, which may even involve security to be completely safe, you should be ok if you are sensible about where you go and when. The most important thing though is to not show that you are well-off or a tourist if you can help it, especially away from the main tourist attractions. You may not want to walk the streets therefore but get transport directly to the attractions you visit. Attractions to visit may include museums, the zoo, aquarium, galleries and the opera house and cathedral, which are all worth visiting.