There are some general suggestions which need to be carefully considered when deciding to travel by bus. For routes within the city, you may buy your ticket on the bus, but always remember to bring change and bear in mind that city buses are often packed.
In the biggest cities, stops may be announced in English and the bus with a snowflake pattern is air conditioned.
Long distance bus:
In most European Countries, long distance bus is the least used means of transportation, but in China there is still a considerable amount of people who take them.
This type of bus is pretty comfortable with berth, the cleanness of which may vary according to the standard of the bus company. Some of them are provided with led screens, toilet and boiler for hot water, but generally the driver stops each 3 or 4 hours for a break. You will have the luggage near you.
As to shorter routes, you will have reclining seats in mini buses.
"Ticket to ride"
But where to purchase tickets? Except for the local travel agencies, that are supposed to have also updated schedules, you may purchase the ticket at the bus station and sometimes also on the bus. You can buy a ticket on line as well, but be prepared to find websites in Chinese only.
One station, more stations
The oldest bus stations are usually located in the city centres, often close to the railway station, but nowadays, more and more often they are located far away from the centre and much closer to motorway junctions or highway entrances in order to avoid traffic jam. Otherwise the buses would lose too much time caught into a gridlock.
Be aware that in the biggest cities there are several bus stations, therefore check in advance where your bus leaves from.