>You should make follow-up visits afterward to monitor QC.
And working conditions, please. People everywhere deserve to be reasonably paid and have safe working conditions.
My experience is that working conditions are very related to quality. For example, a messy factory is both hazardous and a sign of lack of discipline.
Labor in China is quickly rising in cost, and poor working conditions are being punished in the marketplace. It is not always easy to get more labor, and when you can get it, it's more demanding (shorter work hours, nicer atmosphere, less stressful, etc).
So while reasonable working conditions are a must from an ethical perspective, they are also necessary for purely business reasons.
Visit manufacturers in the US (or other developed countries) to study how they do it. Then, go to China and evaluate the factories yourself. You have to see the factory.
If you don't, many times you won't discover that the "manufacturer" you're working with is nothing more than a trading company, taking a cut.
They won't take you as seriously if you don't show up.
You should make follow-up visits afterward to monitor QC. Have rigorous QC methods and standards, and agree to them beforehand.
Also, consider countries such as South Korea, which are more sophisticated manufacturers than China currently but still offer significant cost savings. It depends on the complexity of your product but it may make sense. Labor is much more expensive in Korea though compared to China.
I can answer any other specific questions people have.