I spent a month in Matapalo, Costa Rica in a sea turtle hatchery.
Here’s my advice:
Make sure your daughter knows what kind of journey she’s in for. Get her a phone plan that will work reliably, plus some numbers on paper and/or memorized. For a first-time traveler, it might be best to pick a country whose primary language she’s fluent in. Lastly, be prepared for work that might be physically demanding.
To illustrate: In my case, I knew that I’d be picked up from the airport in San Jose. I had no idea I’d be traveling across the country in a bus for hours on my second day. I was nineteen, but it was still quite disconcerting – especially as the stops, as far as I could tell, had no names. I’d been told I’d be met my a member of staff at my destination, but the only person waiting at the stop was an older guy who smiled a toothless smile and pointed to his pickup – which, being white, was the vehicle I’d been told to look out for. I had no way of communicating with him (or anyone else), and getting in that car did not feel safe at all.
This is not to say I didn’t like it. I got to ride horses on the beach, hold a wounded toucan’s beak while he was treated with iodine, go zip lining and white water rafting, drink from a fresh coconut, paddle around in a clear little pool with butterflies zooming overhead, and carry baby turtles to the sea. I even made some friends – I’d do it all again in a heartbeat.