I just asked my better half (she is from SP) and says (as
RafKa ) already pointed out to definitely make your way to
Beco do Batman.
In terms of safety, you will be fine but it is good to have a bit of street smarts - such as
- plan your route before setting off so you know where you are going and do not look lost. Re-plan / review your route in shopping centres if needed.
- Take your camera out only when taking photos and try to avoid walking around with them exposed.
- If using a rucksack make sure you put in on with both straps to avoid the risk of something grabbing one end and making off with it.
Having said the above, Vila
Madalena is considered a safe area. If you are planning on going to Sé or Vale do Anhangabaú it is not recommend to take your camera out as these places a quite near to Crackolandia and more rife with crime.
The Mercado Municipal is also a lovely spot to visit (not necessarily for graffiti) but would not recommend taking photos with a pro camera - as this is a very touristic area the crime rate is a bit higher.
If you have any specific questions, please do not hesitate to let me know and we will try to help out as much as possible.