This negotiation is not only about the price but some other things which may have very big influence on your business. In fact most Chinese goods are not expensive.
Even I told price is not the most important but for negotiation I still think we should start from the price. Before do that you should do some research on the Chinese supplier market. How many suppliers~both factories and trading companies, of course I am not telling you to count them one by one and got a number. Then do some research about their price and the description of their goods. At that time I think you are already clear about your target price. Then do it, start from the one who interests you most and try your best to see if you could get a satisfied price, during this your research comes in handy, you can use this to persuade the supplier to give a you good price. But remember never being too much, if you forcing their price too much they may change some of the material difficult to notice to reduce their cost.
Second, quality. As we all know if we buy some rubbish, we will lost our customer, so find the good quality supplier and try their samples, after you tried you could select whose goods if for you. And before you place your order you need to emphasize the quality to your supplier as more as you can, or they may supply you some low levels goods instead high quality one.
Third, delivery time. All the business man who have experience in importing from China may have that experience: you have formulate the delivery time and supplier agreed, but when the delivery time comes, you goods are still on production or still on material purchasing part. So before you place your order, do not forget to repeat the delivery time. And if the delivery time is 30 days, I suggest you should ask the updates at least three times. Especially for some seasonal goods. You can imagine, you ordered lots of gifts for Christmas and hope to sell all of them during the festival, but when you have prepared everything but your goods are still on production and when they arrived the Christmas already passed. That is disaster.
After sale service, since most of factories are live on OEM business, they do not sell the goods to final customer, so normally they do not think they are in charge of the after sales service, and when something bad happens, you may need to take this risk by yourself. So before you place your order, you need to ask them how long their warrant can be? How do they manage the warranty. And write this in the contract/PI is important. When some emergency happens at least you could recover some of your losses.
If a supplier can satisfy all that condition, then you’d better never give them up. To be candid in my opinion most suppliers can not match all that conditions