What a timely topic, shipping packages. Well I have lived in China for 11 years now and how I do this has changed dramatically over the years. It's much easier now in some ways than it was 11 years ago.
Let's start with the fact that anything you think you really need from back home, can most likely be purchased on-line right here in China, and that will save you a ton of time and money. Check on-line first. Next, I can only speak to shipping from the US to China and vice versa so if you are not from the States, this may not apply to you.
If you plan to ship from the US the best and cheapest method is USPS. Yes, that's right, the good ol' post office will do just fine. They have flat rate boxes to China (and many other countries) pick a box, stuff it full and ship away for one price. Box sizes vary and so does the cost depending on the size not the weight. http://www.usps.com/shipping
My preferred box is called a "game box," it is not wide but it is tall and you can stuff many items into it. Do not ship liquids, bad idea. Do not ship breakables, again a bad idea. Never ship things that can not be replaced for obvious reasons.
Fill out the forms as instructed, but be sure you are fairly generic when it comes to the customs form. If you give too many details you may end up with too many questions when it gets to customs. It's better to say OTC meds various, than to say 10 boxes of Tylenol Cold and Flu OTC. If you put a brand name it can ring bells and cause your box to be delayed. If you have clothing take off all tags if the items are new and do not claim it as new, used is better. Label it used clothing various. It's just better to be generic.
Your box will ship priority mail so expect it to take 3 weeks, that is normal. What I have done for the past 6 years is to ship boxes back to China when I first get to the States so they will be in China when I get back. So far it's worked well. You can track the box as it leaves US customs, and then track it once it clears China customs but there is a period when you won't see anything. China does a good job and even the few boxes that were waylaid were not China's fault.
One point to make clear, make sure your custom forms are clearly seen on the top of the box. If the person at the post office puts them anywhere else it can delay things. Make sure you write clearly and that the address is in Chinese and with a local phone number, if there is a problem they can call someone. Finally, keep all paperwork until you have your box.
Shipping from China back to the States, this can be a little trickier. Many items can NOT be shipped and it will depend on the post office you use in China. Yep, I use China Post and they have been fine. You must bring your items NOT boxed and then you box them at the post office because they want to see what is in the box, and they will give you a box to pack things into. I have been told I can't ship used clothing, or medications, or food. They are rather picky. If you need to ship those items it will cost you more but you can do it using any of the "air" shippers like Federal Ex. Be prepared to pay a lot more. China Post has two options, the quick option will get a box to the US in about 3 to 4 weeks, the very cheap option can take up to 3 months (yep by boat).
When shipping locally (in China) China Post is fine and they have been known to get an item from Beijing to Guangzhou in a day or two. They are actually very good but you will need someone with language to help you if you don't speak Chinese.
Costs, well it depends, I can ship a game box which holds about 20 to 25 lbs, for about $100. For me it's a no brainer, shipping two boxes verses dragging two suitcases...I prefer to leave the suitcases behind. I have also started buying items locally (in China) and not bothering with trying to get them from "back home" it's about the same cost and it's actually faster.
My worst experience was a box I shipped from CA to China and the people in San Francisco (SF) customs lost the box. It took me 3 months to get them to try to locate it and finally they gave up and so did I. However, later that same week China Post contacted me that they had a box for me. It had somehow gotten damaged but made it to China without being tracked about the same time the SF people had told me the box was lost for good. I have never figured that out. The tracking documents had been placed on the bottom and so they eventually were damaged and hard to read. Furthermore the box had water damage which made the address illegible, thankfully I always put my address inside, so they were able to find me. Some items were slightly damaged but I have a habit of packing stuff in zip-lock bags so that gave my things added protection. All in all, I got my box a little later than planned and with some items a little banged up. However, that was my worst experience to date.
Good luck on your shipping adventures, don't stress it and be willing to let it go if things get lost or damaged, it's the risk you are taking. My advice, if you must have it, bring it with you or see if you can find someone else to do that for you. Learn to live with what you can get locally, in the end that will make your life here much easier.
