Tibet was opened for tourists only in 1985. Before this, it avoided influence from the western world and developed its unique culture & religion independently. To see a place like Tibet now, before many modern changes take place, is certainly a unique experience. 
Its name, the “Roof of the World” is no idle statement. The valley bottoms of Tibet are higher than the highest mountains elsewhere. Its snow covered plateau are the highest in the world. Apart from the Everest, which Tibetans see from the other side, many mountain ranges are over 4,500m. Tourists can fly right into Lhasa from Kathmandu, taking one of the world’s most dramatic flights across the Himalayan range. Lhasa (3,650m) Tibet’s capital city lies in the highest plateau of the world amid arid wilderness. 
Travelling to Tibet is an incredible journey in which one can see the world's highest mountains, travel on the world's highest plains, meet nomadic herdsmen and pilgrims and walk amidst the burning butter lamps & chanting monks of Tibet's ancient and legendary Buddhist monasteries. This is a wonderful and amazing trip. However, if participants are not up for a bit of adventure or for accommodations & amenities that may be far from perfect, then perhaps this trip is not for them or their trip should be limited only within Lhasa city. "Cold & dusty" is the comment of many people who have visited Tibet. While the trip to Tibet is not easy, it is well worth the effort. Even the most jaded traveller may feel like a neophyte tourist. 
Many of the conditions described here are still controlled by the Chinese government. The trip is considered "Luxurious" by Chinese standards, a definition with which it is very hard to agree. Travellers have sometimes been disappointed with accommodations, guide services and meals; Even writing about the lack of hot & cold running water or flush toilets seems rather trite, when the conditions tourists experience are far superior to local standards and hence, luxurious indeed in comparison. However, to be forewarned is to be forearmed. Most folks have better experiences, when they know what to expect. 

Accommodations

The clients should not have high expectations of these and they will not be disappointed. Camping trek style might be a better alternative but currently it is not a Chinese-offered option, where the accommodation is available. The Chinese-built luxury tourist hotels that are found in Tibet are large, cold (figuratively & literally) cemented buildings set amidst fenced-in compounds. 
The hotels in Zhangmu and Xegar and most guest houses in Tibet are poorly kept with dirty carpets, broken windows and a feeling of abandonment, that permeates the lobbies & bedrooms. Hotel Lhasa (former Holiday Inn) and few other hotels in Lhasa are comparable to average Western lodging. While all the hotels have rooms with bathrooms, some hotels/guest houses do not routinely have either hot or cold running water. Several hotels (except in Lhasa) have hot water for bathing available during certain hours in the evening only; these hours of availability are announced, when guests arrive in the hotel. 
All hotel guest rooms are provided with a thermos flask of hot water for tea as well as comfortable beds with lots of warm blankets. While all the hotels are wired for electricity, power in some of the hotels/guest houses are limited to a few evening hours. Taking a flashlight along is a must. All hotels provide toilet paper, but for toilet stops during the day while on the road, it's a good idea to take some toilet paper along. Except the Lhasa Hotel in Lhasa, none of the hotels are heated. People wearing down jackets & hats while eating dinner or breakfast is a common sight. In November, the mean temperature in Lhasa goes from -4°C to 12°C. In August, the mean temperature ranges from +8°C to +22°C. 

Food & Snacks

While traveling in Asia, one must be careful about food & drink. Many travellers have problems with diarrhea in Tibet. Despite the most conscientious efforts, they may still come down with the dreaded ailment. Nevertheless, there are ways they can decrease the probability of getting sick and limit the bad effects of diarrhea once it has started. We recommend to carry iodine solution or tablets to purify drinking water. Normal concentration of chlorine tablets are not strong enough to kill giardia, a common cause of diarrhea in this region. No non-chemical filters eliminate viruses such as hepatitis & therefore should not be used alone to purify water. All boiled or tea water is probably safe. Ice cubes should not be taken unless one can be sure that they are made from boiled water. Many people forget that contaminated tap water used in brushing teeth could be a source of diarrhea. Any water going into the mouth should be purified with iodine or previously boiled. 
Foods that come hot & recently cooked are best. Foods that are peeled or skinned are also usually safe to eat. Especially when visitors are not sure under what conditions the food has been prepared, they should avoid cold salads or other not recently cooked food that may have been sitting out for a long period of time. Salads cleaned & soaked in iodine are also safe. However, it is hard to determine whether or not the food has actually been soaked or whether the restaurant personnel just want to please the clients and tell them what they want to hear. 
Good restaurants are not available on the highways in Tibet. Therefore, we recommend clients to carry lunch boxes. However, realizing that lunch stops during the tour can be a bit unappetizing, bringing own snacks would be a great idea. They should bring foods they like & can eat easily (i.e. crackers, cheese, cookies, chocolate bars, granola bars, soup mix or peanut butter). But it is advisable not to bring too much. Ascending to high altitude many people find their appetites greatly diminished. This is a mild symptom of altitude sickness, so they should not be surprised if they are not very hungry. Also, unlike trekking, they will not have a lot of exercise as they will sit in the bus and watch the passing scenery most of the time. 

Guide

The Chinese/Tibetan guide provided for our groups may not speak very good English and may not know much about the local monasteries, history & culture. For best information, we recommend clients take a guidebook along on the tour. The Tibet Guide by Stephen Bachelor and the most recent one, Tibet Handbook by Victor Chan is an ideal book to take along. It gives general information about Tibetan culture as well as specific information about the usual sights. Unlike Lonely Planet's Tibet: A Travel Survival kit, which gives more logistics about travelling around Tibet independently. The Tibet Guide & Tibet Hand Book concentrates more on Tibetan culture & sacred places. Both books are useful. Also quite useful is a route map, to know where they are going and have been each day.

Clothing

We recommend the following clothes to be brought along:

Altitude Sickness

As most of the places in Tibet lie over 4,500m, clients are likely to experience some of the minor symptoms and discomfort of altitude sickness (headache, mild nausea, and loss of appetite) until their body is adjusted to the elevation. This can take from few hours to a couple of days, depending on the individual. They should take it little easy first couple of days and take in plenty of non-alcoholic liquids. This helps the body to acclimatize faster. 

Visa

To apply for China visa the passports must be valid for more than 6 months. A Group Visa is normally issued in Kathmandu. As per new regulations, the normal Chinese visa issued abroad is also good to enter Tibet from Kathmandu. We arrange for issuance of the Tibet permit, which is required in any case. For the Tibet Visa procedure, we require following information by fax/email at least 30 days prior to the arrival in Tibet: 1) Name as in Passport. 2) Passport Number. 3) Nationality. 4) Date of issue & expiry of the passport 5) Date of Birth. 6) Occupation. 7) Sex. We also require the photocopy of the passport by fax or email (as an attachment).