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I am extremely eager to travel and see the world, yet I am nervous about going to a strange country where I am not fluent in the language. I'm trying to travel to a wildlife refuge near Cochabamba, but I would have to go into the city of Cochabamba and take a bus to where I want to go. Is this safe? Is this stupid?
If you have an ounce of common sense, which it sounds like you do, I think you can make it to the refuge okay. Sometimes, when you're volunteering, the center or facility will help you get there, be it someone meeting you or arranging travel for you or just helping you break it down to exactly what you need to do to get there.
It always helps to at least have a conversational dictionary. Being nervous is normal and you'll easily get over your initial nervousness. Most people are nervous their first trip but as you move along in your journey you'll just keep gaining more and more confidence.
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I wouldn't let the negative stories deter you. Just use your common sense and intuition, always be aware of your surroundings and don't be afraid to ask for help.
This is good advice. And remember, there is danger all over the world, everywhere. You
do have to use your common sense, maybe more so in some places then in others, but all you can do in life is take care in what you do and make informed decisions.

Oh, and remember, you definitely will not be the only English speaking person in Cochabamaba.
Where is the refuge?