Flights to Sao Paulo Brazil are either annoying or plentiful depending on the area where you live. Americans (citizens of the United States, that is) have the benefit of being relatively close to their fantastic southern neighbor. Flights to Sao Paulo are usually via Miami, which boasts both a large Brazilian community as well as proximity to this destination. For this reason, flights from this city will tend to be cheaper. You can also save by searching for lower priced tickets during seasons which are slower for tourism, specifically from the middle of June until the middle of September. From the months of March through June, you may also get tickets which will be relatively cheap, though not as cheap as the previously cited time frame. Forget about getting a cheap deal on flights to Sao Paulo anytime around Carnaval, which is held in either February or March. This is when the biggest party in the world happens, and air tickets to Brazil will be expensive up to several months before the event. Keep in mind that the seasons are opposite in the southern hemisphere, which means February is high summer in Brazil.
For travelers departing from Europe, you can find good deals if you depart from Lisbon. Brazil was once a colony of Portugal and they two countries still share Portuguese as a common language, so many Portuguese visit Brazil and vice versa.
If you happen to live in Japan or east Asia, good luck! You are basically on the exact opposite side of the globe from Brazil; if you drilled a hole straight down through the earth like in the old cartoons, you will wind up in Brazil. Judging from Bugs Bunny’s time of a few seconds to reach China by drilling through the earth, it might be faster than taking the 30 hour+ flight to Sao Paulo Brazil