1) Lock your device - always. Add a PIN protection to your SIM card and enable password protection on your phone
2) If you carry something like an iPhone, keep it in a nondescript case
3) Dump the white iPod headphone - nobody needs to know you have an iPod
4) Don't use open hotspots, and if you, pay for a VPN service
5) Never, ever logon to Ebay, Paypal, bank services or anything else you don't want to share, unless it's on your OWN pc, and on a secure connection. Keysniffers are everywhere in the world.
6) Don't use your primary email address on your phone. If someone DOES find it, they could be changing your Paypal email address in a few minutes. Use a disposable addres. If possible, use Gmail and use their account information feature in the bottom of the window to check for weird account access.
7) If you are carrying files you don't want to share, add them to a Truecrypt file and don't name the encrypted file "top secret files".

FWIW; these tips don't just apply to China, they are applicable everywhere in the world. I wouldn't be too afraid of Chinese intelligence, it's the common scammer you need to worry about.