I have sent and received packages to and in China from abroad for 15 years now and never had a problem, nothing missing, nothing stolen. But maybe because I do worry about details, I bothered to learn what was needed to insure prompt, fast delivery of all my parcels.

There are a few simple rules to follow:

1.- Have your name, address and cell phone number (I even have my email address) written in Mandarin and in English. Instruct sender to download it, print it and paste it to the outside of box, also place a copy inside. Many Postal employees do not speak English at all, so if your parcel is addressed to you only in English, it will sit at the local Post Office waiting for someone who can translate it, maybe for a month or two.
Make sure your address in Mandarin has "CHINA" written in English at the end. The USA Postal Serrvice sent one of my parcels to Thailand once because they could not understand what was written, Thailand forwarded to China without a problem.

2.- Do fill the Custom declaration form correctly and in full. Do not leave anything out. Parcels can be opened for Customs inspection, anything not listed, or not correctly listed, will be assumed contraband, and further delay delivery.

3.- Learn what is allowed, and what it is not allowed, to be shipped into China or out of China. Then do not try to be a smart one.

4.- Instruct sender not to use regular stamps on your parcel, but use meter tape instead. Some parcels disapear because of "fancy stamps" on them.

5.- When visiting your local Post Office, be nice to employess, smile a lot, so they get to know you, and your name and address. You will be surprise afterwards at the quality of service you will get. A Coke to an employee when delivering something to your apartment will insure good future service from them.