Be sure to bring warm clothing as nights and early mornings can be quite chilly to downright cold in winter months. Bring all the film, medicine, cosmetics, personal toilet items etc. A small first aid kit is also a good idea. This can take from a few hours to a couple of days, depending on the individual. Take it lightly , drinking plenty of non - alcoholic liquid will help.
Proper hydration is critical to acclimatization.
The journey from Kathmandu to Lhasa by road should be viewed as an adventure , not sightseeing tour by bus. The road itself was poorly constructed and is prone to landslides , particularly from June through September. It can be very dusty and some kind of face mask is a good idea. As you drive to altitudes of over 17000 ft. at some points altitude sickness becomes a real possibility and most will feel some symptoms. Hotels are basic with showers, flush toilet, a small shop, a restaurant and laundry facilities only.