Photography in the jungles and rainforest's of Costa Rica can be very difficult. On sunny days the light is very contrasty. One secret to getting nice photos on these days is to look for small windows of nice lighting and focus in on that. If you try and include the whole scene on a sunny day you'll most likely end up with patches of brights and darks that are very difficult to combine in a pleasing composition.
Shooting in overcast conditions gets easier, the light is more even, but it can still be pretty dark in the thick forests and there is still so much going on in any scene that finding a small area with limited distractions is still your best bet. A tripod and off-camera flash can help here as well. What I look for is a beautiful quality of light and a background that isn't too distracting. To me, pretty much anything can be stunning in the right light.