Useful info

Local Time = UTC +8h

Electricity supply in China and Asia is 220 volts, but sockets with adapters are available in the washrooms of many luxury and medium-grade hotels. 

Tibet uses the Chinese Renminbi (RMB), or Yuan. The exchange rates change often, so check the current rate before you go. Siia link
In Tibet, the only place to change foreign currency and traveler’s cheques is the Bank of China. If you are travelling upcountry, try and get your cash in small denominations: RMB100 and RMB50 bills are sometimes difficult to get rid of in rural Tibet. If you don't like the idea of turning up at the border with no Chinese currency, you can buy cash from banks in Hong Kong and the Bank of China in large cities.
Credit cards are not recommended as a way of payment in Tibet. Flights to Lhasa can not be paid by a credit card. The Lhasa central branch of the Bank of China is the only place in Tibet which provides credit card advances. A 4% commission is usually deducted and the minimum advance is normally RMB1200.
Several ATMs in Lhasa and Shigatse accept foreign cards. Check before trying your card, as many ATMs can only be used by domestic account holders. Cards are occasionally eaten, so try to make your transaction during bank hours.  Read more >

Tipping is not common in China. If you try to leave a tip in a restaurant, than most likely the people will run out of the restaurant after you, to give your money back. 

Tibet has similar seasons to China, though with lower temperatures due to the higher altitudes. Winters (November to March) are cold, with the average temperature of -2°C in January, but there isn’t all that much snow. Summers (May to September) have warm days with strong sunshine and cool nights. Even summer days can be chilly at higher elevations. During spring and autumn you need to be prepared for four seasons in one day, including the possibility of snowfall.
There are some regional variations; northern and western Tibet are generally higher and colder. The monsoon affects particularly eastern Tibet, from mid-July to the end of September.

What to Pack
Sunglasses, sun lotions, chapped stick, hat, layered clothing and down-filled coat. The sun is very strong during the day but the temperature drops at night. Wear comfortable walking shoes. High-calorie snacks like cookies, chocolate and candies should be packed in advance, also.
The weather on the plateau is quite changeable and there is a large temperature difference between day and night. It is very important to keep warm and avoid getting chilled. We recommend that during the day you wear loose, nonbinding clothes that are layered along comfortable walking shoes and absorbent socks. If possible, take with you extra clothes for emergency. A brimmed hat and a pair of sunglasses are advised to protect you from the ultraviolet radiation due to the thin air. Skin care products with sun block are a must!

Medical care in Tibet is extremely limited. For a medical emergency, call the SOS International Ltd., 24-hour Alarm Center in Beijing at telephone (86-10) 6462-9100 and in Shanghai at (86-21) 6295-0099 for advice and referrals to local facilities. SOS International Alarm Centers can also be contacted in Hong Kong at telephone (852) 2428-9900. Serious medical problems will require air evacuation to a country with state-of-the-art medical facilities.

China doesn’t officially require any immunizations for entry into the country. However, the further off the beaten track you go, the more necessary it is to take all precautions. The World Health Organization (WHO) requires travelers who have come from an area infected with yellow fever to be vaccinated before entering the country.

The number-one rule is: be careful of the water, especially ice. If you don’t know for certain that the water is safe, assume the worst. In urban centres Tibetans, like the Chinese, boil their drinking water making it safe to drink hot or cooled. In the country and while trekking, you should boil your own water or treat it with water-purification tablets, as livestock contaminate many of the water sources. Milk should be consumed with suspicion as it will be unpasteurized in the countryside, although boiled milk is fine if it is kept hygienically. Soft drinks and beer are always available wherever there is a shop, and these are always safe to drink, as is tea. Locally brewed beer, chang, is another matter. It is often made with contaminated well water and there is always some risk in drinking it.

Security & Safety
China is one of the most secure destinations in the world! The delinquency is low and even in the late evening you don’t need to be afraid of anything. Typically there aren't many "tourist traps" as the Chinese people are very honest. The main tourist spots will try to get extra money out of you, if they can. Stay away from wild animals. Some animals are in the habit of racing along with cars. This may seem amusing and the animal may give the appearance of harmlessness. But it is not always so and a direct encounter with wild animals may turn out to be very dangerous.

Food & Drink
The traditional Tibetan diet is largely limited to barley, meat (mutton or yak) and dairy products, with very few spices or vegetables, although brutally hot chili sauce is often served on the side. Even good Tibetan food is monotonous with most Tibetan restaurants serving nothing other than thukpa (noodle soup) and tea. By comparison, Chinese restaurants in villages often put out some excellent food. Some travelers feel that Hui (ethnic Chinese Moslem) places are cleaner because of halal food laws; they can be recognized by the green flags and crescent moons.

While traveling, be prepared for the bus to depart late or break down. Carry a snack on short trips and enough food for a few days or a week or more for longer journeys, such as to Mount Kailash. Instant noodles are convenient even if you don't have a camp stove. They can be eaten cold or softened with boiled water. Tsampa (roasted barley flour) is an ideal travel food because it's already cooked. Eat it mixed with tea, butter and salt, or as a high energy snack by mixing it with water, milk powder and sugar.
Tea houses are an important social venue in Tibet, and offer a chance to sit down and relax. The tea houses in the larger towns and cities offer sweet tea, or salted; in the villages you may only have the option of salty tea. The line between a tea house and a restaurant is blurred and many also offer thukpa.

A selection of popular Tibetan fares and drinks:
*  Momos – steamed or fried dumplings, filled with meat or vegetables
*  Tingmo - bland, nearly tasteless steamed bread 
*  Thukpa - a hearty noodle soup with veggies or meat 
*  Thenthuk - thukpa with handmade noodles 
*  Pöcha - salty tea churned with Yak butter, a Tibetan staple and a rather acquired taste for most Westerners 
*  Chang - Tibetan beer made of barley. Beware of chang: the yeast is still alive in it, and will carry on fermenting and producing alcohol in the warm temperatures of your stomach! Usually no germ risk, since yeast prevents bacteria proliferation.