From www.wfft.org:
DO NOT have photos taken with wild animals being used as photos props, go to animal shows, visit elephant riding camps, or visit tiger temples/petting zoos.
DO NOT purchase animal souvenirs, including snake or tiger wine, bush meat, or ivory. When the buying stops, the killing stops too.
DO your research! Only visit rescue and rehab centers.
DO tell family and friends. Write a story for your local newspaper back home describing your experience in Thailand.
Travels in Thailand 