You must include the following in your application:
1. Your passport with at least one pair of blank facing pages and at least 3 months validity beyond the duration of the visa you are applying for and in any case a minimum of 6 months.  If you don't have this you will need to get a new passport first. If you are entering on a visa that will be converted to a Temporary Residence Permit, it would be wise to have at least two pairs of blank facing pages. 

2. A passport photo – if you buy one from a recognised passport photo retailer you will ensure that you get photos of the correct dimension and background colour. 

3. The  application fee (see visa fees)

4. When applying within China, photocopies of your passport id page, your current visa, and your last entry stamp; and a residency registration

As explained in visa types, for visas other than tourist and transit, additional documentation must be submitted – as explained in Visa types . The Chinese organisation that you are involved with will need to organise these for you.  

Additional proofs are sometimes asked for such as for the period around the Olympic Games though they can be asked for at any time at the discretion of the PSB office.  Some nationalities may be asked for these proofs, others not. Generally, you do not need to undergo a physical examination (medical) for Z, X, or F-1 visas, however, there does seem to be a provision whereby this can be required.   You might be required to show that you have sufficient funds for the duration of the visit at the rate of US$100 a day; hotel bookings or other accommodation arrangements for the full period of the visit; onward travel arrangements out of China; an invitation letter.  In these circumstances, if you are planning a budget trip, pre-book some youth hostels and any travel you can to show that you will need less money than US$100 a day.  If you have friends or business acquaintances, get invitations.  Of course, there are no guarantees.

If your application is accepted for processing you will be given a receipt.  If you want someone else to collect you passport you must give them this.  Should you lose the receipt only you can collect your passport and you will need some other photo-id.

 China Visa Application Requirements
Requirements for China Visa Application at China Embassy/Consulates in USA
Requirements for China Visa Application at China Embassy/Consulates in UK
Requirements for China Visa Application at China Embassy/Consulates in Canada
Requirements for China Visa Application at China Embassy/Consulates in Australia