More than 95% of the population in Tibet speak Tibetan languages. There are 3 main dialects respected in Lhasa & Shigates districts, northern Tibet and east Tibet. Many of them can speak fluent Mandarin. Some of the staffs, businessmen, students and monks speak English and they'd like to talk with foreign tourists in English.
It is a courtesy that when Tibetan people meeting and greeting to you, they will put their hands palm to palm in front of chest and stretch out their tongue to show their respects to you. You may put your hands in front of your chest and say "Tashidele" (good luck) to them.
When Tibetan people present you a cup of wine, you should dip your ring finger in the wine and flick the wine to the sky, in the air and to the ground respectively to express your respects to the heaven, the earth and the ancestors before sipping the wine. Then the host will fill the cup, and you take a sip of the wine again. After the host fills your cup three times, you will take the whole cup of the wine.
The main food and meat in Tibet are highland barley, beef and mutton. Tibetan people never eat horse meat, dog meat and donkey meat. In some areas in Tibet, people do not eat fish, either.
Smoking in Tibetan Buddhism monasteries is strictly banned. It is not allowed to touch the statues of Buddha and religious articles or take pictures of them. In addition, everybody should walk clockwise around monasteries or other religious objects like pagodas, Mani-stone piles, incense-burners, etc.
Eagles are sacred birds in the mind of Tibetan people. And also the sheep or cows with red color or colored strips on their body are considered as sacred animals. It is forbidden to disturb them or do harm on them.