There is no simple right or wrong answers on this topic. The challenges are obviously there no matter sourcing from or marketing into a foreign country as remote as China. However, with cost savings in double or even three digits percentage wise for certain commodities, it is surely worth of the effort to many companies.
Just like the case you are trying to hire someone, the good old way may be to find the candate through your network. It would be nice if you know someone who is currently using a supplier with satisfaction and willing to make the recommendation. The rating system on MFG.com serves similar purpose as alternatives.
Among all things important and learned through low cost country sourcing, perhaps it would have to come down to three things, i.e. communication, communication, and communication.
1. Initial communication
Write an email to explain your objectives and set up a time to call with clear agenda. Take advantage of phone conversations to fully probe all issues interested and make assessment of the comfort level in terms of language, attitude, and personality. Without the chance of face to face meeting, you have to utilize telephone to find out if it is the right person or organization that you would feel comfortable dealing with in long term.
2. Ongoing communication
Besides ongoing email communication, try to set up periodical conference calls. This is tough due to language and time difference. However, this is the only way to avoid various misunderstandings due to lanugage challenges and cultural differences. For ongoing projects, set up at least a weekly conference call though sometimes there is not much urgent matter to cover. Verbal and interactive communication places great importance in international project management and helps building relationship which is a key to business in China or almost everywhere.
3. Writen commuincation
It is always helpful and a good way for house keeping to track things in writing, i.e. writen agenda sent before conference calls, meeting minutes afterwards, project tracker updates if multiple projects involved. For technical matter, ftp sites could be helpful for consolidating all latest documents at a single place for access and download.
It may sounds a bit awkward that a "buyer" has to be so proactive in the process management normally you would not do in your domestic sourcing. However, this is the best "trick" in low cost country sourcing. The alternative could be using a middle parties, e.g. trading house, sourcing office, or a manufacturer's rep which spend most of their effort in the above value added processes to make projects successful for an award through commission or makeup. Hope it helps.