The Tibetans are among the easiest people to get along with in Asia. But there are still some cultural considerations you require to take note of when you travel in Tibet.
1. Don't photo anyone without getting permission first!
2. Always go round gompas and other religious objects clockwise – keeping shrines and chortens to your right.
3. Don't touch or remove anything at altars.
4. Don't take photos during prayer meetings. At other times always ask permission especially if making use of flash. The larger monasteries charge photography fees.
5. Don't wear shorts or short skirts in monasteries and remove hats when you enter a chapel.
6. Don't smoke in a monastery.
7. Don't eat dog, donkey or horse in Tibet.
8. Be aware that Tibetans often gesture with their lips to give directions, so if a member of the opposite sex pouts at you they're just showing you which direction to go in!
(Tibet Travel Expert)