Last year I did my own visa application for China. I used the info PVS sent me to know what to put in each box. Just follow those instructions. Easy-peasy. The application also asks for a copy of the trip itinerary and a copy of the airline itinerary with the flight numbers. I took my application into the Chinese visa office in Sept. and they didn't want to keep those documents -- just kept the main application and the passport. They gave me a receipt with the processing number and the cost. Two days later I went back and got the passport with visa glued in. I paid with a credit card. It took me longer to park and walk into the office than to wait in line and be processed to get the visa. Don't be afraid to do it yourself.
Be sure you check the multi-entry visa. Depending on the trip you take, you will probably use/need the multi-entry visa. The visa is good for a year, so why not get it? There is no additional cost.
Unfortunately, one cannot mail in a visa application to the Chinese visa office. Each passport and application has to be hand carried -- even by PVS. Every time I go to the Chinese visa office, there are lines of couriers with duffle bags absolutely stuffed with passports and applications. These are bundled together with rubber bands (I assume according to tours and/or companies that get folks the visas, like PVS). The couriers then go back in two days and retrieve the passports with the visas inside.