If you enter Lhasa by train or flight from a Chinese city, such as Beijing, Shanghai, Chengdu, Xining and etc, you have to apply for a Chinese (tourist) visa firstly. You cannot do the Tibet permit application by yourself; your Tibet tour operator will do it for you. What you have to do is to send by email the clearly scan or photo copy of your valid passport and Chinese visa to your Tibet tour operator, note this must be done at least 15 days before the trip; while, if you plan to visit Mt. Kailash, this has to be done at least 25 days beforehand as the military permit really takes long time.
You have to tell your tour operator your occupation too, because journalist, politician cannot travel to Tibet via tour companies. People of those occupations have to refer to Tibet Foreign Affairs department for a tour to Tibet.
When apply for your Chinese visa in your home country or any other third country, make sure NOT mention Tibet in the visa application form, otherwise it will be very difficult even impossible to get the visa approved, because overseas Chinese Embassies do not expect you to visit Tibet because of sensitiveness there. We recommend you to just write some Chinese cities name in your Chinese visa application form, cities like Beijing, Xi’an, Shanghai or Chengdu.
On the other hand, if you enter Tibet by overland or flight from Kathmandu, Nepal; the Chinese visa and Tibet permit rules are totally different compared with entering from China side, for more detailed info, please refer to our page of Tibet permit from Nepal.