These are the ruins of Ta Prohm that were made famous by the movie, Tomb Rider. This was one of my favorite sites among the vast ruins of the Ankor complex just outside of Siem Reap in Cambodia. The two big challenges at this location involve lighting issues, because you are in the jungle, and the bus loads of tourists who get in the way. My advice is that you hire a tuk-tuk driver the night before you go here to pick you up before sunrise. Photograph the rising sun from the reflection pond at Angkor Wat and then head over to Ta Prohm to beat the crowds. Make sure that you hire your tuk-tuk driver for the whole day. He will wait for you while you explore each ruin and then return you to your hotel at the end of the day for a modest fee that you pay when you are done with your tour. Negotiate your fee when you hire him and it's nice to treat your driver to bottled water or soft drinks during the day. Also, the night before your visit, do not over cool your hotel room. It can be very humid in Cambodia and a cold lens will fog over when you go outside.
Here's another great tip that Andy Teo reminded me of:
"if you pop round there at 5pm (there's a place before you enter the Angkor complex where you get your tickets, kind of like Disneyland) the night before you can pick up a pass which lasts the whole of the next day, so you can get in in the morning without queueing."