I volunteered on the GVN Brazil Program this September and it was by far the most rewarding, eye opening and heartwarming experience I've ever had. GVN supported me before, during and after my trip and is always there to answer any questions you may have.
During my stay in Rocinha, I was working and living with wonderful volunteers from all over the world. I did the Teaching Program so I got to teach smart and enthusiastic kids every afternoon, as well as equally amazing adults some days of the week. At night we got to do some locals classes which was a lot of fun as well, I've never met more welcoming and friendly people than the ones in Rocinha!
The children running up to you yelling "Teacher!", grabbing your hands and hugging you, will put a smile on your face every single day. The lessons are great because the kids are genuinely happy to be there and eager to learn, especially when you put in the effort to make everything interesting for them (singing songs, playing games, reading stories, letting them act things out and draw, asking people to come up front to point things out etc.).
Arriving in a favela by yourself is daunting of course, especially when you don't speak Portuguese. All I can say is that it's SO worth it to jump in head first and go for it, you will not regret it. Sure, it won't always be easy but that just makes you a stronger, more independent person. The people you meet, the experiences you have, the things you visit in Rio will stay with you forever. My main advice: stay as long as you can!! I was only there for a couple of weeks and I so wish I could have stayed longer.
Thanks to GVN and the local Brazil Program, I can't wait to come back some day!!