Because it rains a lot June and August, and since winter lasts from December to March, and because the typical tourist would like to take picturesque photos, the optimal time for travelling in Daocheng County is April to May and September to October.
There are two main points of origin for visiting Daocheng County: Chengdu, the provincial capital, and Kunming, in Yunnan Province.
The Chengdu > Litang > Kangding > Daocheng route is about 800 kilometers, and takes two days by bus. This trip requires an overnight stay at Kangding before proceeding on to Daocheng. The ticket is usually only issued for the Chengdu > Litang > Kangding leg, meaning that you will have to purchase a separate ticket for the Kangding > Daocheng leg of the journey. For this reason, it is best to purchase the second-leg, or Kangding > Daocheng, ticket the day before, in order to be sure of a place on the bus. The leg from Kangding > Daocheng itself takes 12 hours. However, since the elevation between Chengdu and Daocheng is dramatic, most travellers are advised to spend more than one day in Kangding in order to acclimate to the high altitude.
The Kunming > Lijiang > Zhongdian > Daocheng route is considered one of the more picturesque touring routes in this part of China. As with the previous route, the traveller is well-advised to spend an extra day or two in the middle of the journey - in Zongdian in this case - in order to acclimate to the high altitude.
The bus service between Zongdian and Daocheng can at certain times of the year be suspended due to local landslides. If this occurs, there is an alternative, more round-about route that skirts around the problem area. This route is Zhongdian > Derong > Xiangcheng > Sangdui > Daocheng, with a wrinkle or two: there is a bus to Derong, but not to Xiangcheng, and there is similarly no bus from from Sangdui to Daocheng.
To get to Xiangcheng, you will have to take a taxi (if there are other travellers, the fare will be reasonable). You will have to overnight in Xiangcheng, then catch the early-morning bus to Sangdui. From Sangdui to Daocheng you will again have to travel by alternative means, but there are local taxis as well as shop owners who ferry travellers between Sangdui and Daocheng.
With a bit of luck, the bus route between Zongdian and Daocheng will not be interrupted; it all depends on local weather conditions.
Due to the daily swings in temperature (mornings and nights are chilly if not cold), layered clothing is a must. In addition, a small flashlight (with extra batteries), sunglasses, sun cream, good walking shoes, and a raincoat or umbrella are essential accessories, as well as any medicines you may require on a daily or an occasional basis. A digital camera with extra memory is also preferred to conventional cameras, unless you plan to carry all of your film supplies with you.
If you have a heart condition or suffer from hypertension or a respiratory disease, you are advised not to travel to the area due to the extreme elevation. For this reason, you should also beware of excessive drinking, vigorous physical activity, and you would do well to eat "lighter" - i.e., eat less meat and instead eat more vegetables and fruit. Never be tempted to eat local wild fruit (berries, etc.) and plants (eg., mushrooms) that you gather yourself, since you run the serious risk of being poisoned.
Lastly, use common sense: observe any posted signs that warn of danger. You are similarly advised to moderate your behavior so as not to offend local religious sensibilities and local customs.