Australian passport holders travelling to Brazil for business or leisure will no longer need a pre-arranged visa from June 17 2019.
Currently, the visa charge for Australian passport holders is US$44 (~A$62) to obtain an e-visa, while applying by for a visa by post or in person at the embassy is $216.
Stick to the tourist areas if you can afford them and don't wander around favelas / poor neighbourhoods (people who hype them up are either ill intended or clueless, looking for trouble).
Keep your belongings close to you at all times, don't use your phone in public, keep a hand on your wallet when walking in crowded places.
Rio and Sao Paulo are good, but the south of the country is the best region to visit IMO. The northeast has the best food.