Panama [1] is a great place for hikes, both casual day trips and major backcountry treks. There are very few developed campsites in the country, however, and few rangers to help out stranded hikers. Trails are often rugged and rudimentary.
Never, ever hike in the forest alone. Go with a qualified naturalist guide. It’s surprisingly easy to get lost, and in some parts of Panama—such as the Darién [2]—getting lost can be fatal.
Also, rainforest trails can be very slippery, and you don’t want to be stuck alone in the forest with even a twisted ankle. I’m embarrassed to admit how many times I’ve wiped out on what looked like an easy trail or gentle stream crossing.
Appropriate gear is key to a safe, enjoyable hike in the tropics. Always camp in a tent, even on the beach, to prevent insect and possible vampire-bat bites. Treat even small scratches with antibiotics; wounds quickly become infected in the tropics.
Hitchhiking is not common in Panama, and it’s just as dangerous here as it is in your own country.
Links:
[1] http://www.moon.com/destinations/panama
[2] http://www.moon.com/destinations/panama/the-darien