Size issue
Most of clients will design their products into A4 size, but unfornately, that is the not the best size for printing it in China, if you could, you may design it 210mm*285mm, or smaller, that will save you a lot.

How to lower cost if your job require some hand work
In China, labor cost may only 1/10 of US, even so, if you job require much hand work, it is still could be expensive; you may believe, larger QTY will make the cost much lower, but in fact hand work is not machinery job, within certain scope, it may simple double when your QTY double, so we strongly encourage clients to design your work with lesser hand job to lower the cost.

Place your order at right Season if you print in china
Better not place your order at Xmas season, better get your work done before that, do not expect anything can be done or done right in China during Feb., because that is Chinese New Year, the season of everybody gone. Also, 1st-7th of May and Oct. are also national holidaes in China.

How can you get right colour you want with a printer in China
You must be very careful, proof confirming is a big thing esp. printed overseas. You must find an agent who have the expertise and resposability. You may let your provider make a proof at smaller size, or use PMS for spot colour.