Always take the public transportation (except at night). You’ll be happy how much money you’ve saved and basically how much of a pro you are (if you manage not to get lost).
In Rio I stayed at a hostel that is on top of a hill in a favela. On the website it shows that it has an amazing view of the coast of Rio. The trouble is that it’s in a favela. I’ve read reviews of the hostel and had local told me that it’s a relatively safe favela, but it’s still a favela. Not only do I look different, unlike in a Spanish speaking country, I don’t speak a word of Portuguese (well that’s a lie, I know like 3). Anyway the temptation of staying there, having a favela experience, and being able to wake up to that amazing view outweighs the fear of danger.
Not being prepared…