Some advice that would be helpful is to get all your ducks in a row.
1.)Schedule the meetings/lunches on certain days and have it planned out before you fly.
2.)Have a quesitonaire made with all the questions that you could possibly think of. If you dont know how many questions are enough, set a number like 3 pages to fill. Stretch that brain!
3.)Tour their factory if they have one.
4.)Try to negotiate a better deal. If you fly to meet them in person, the chance of you getting a better price is much better. It shows that you are serious.
5.)Try to obtain a number or contact route that is more personal that you can call when you want to see whats new, etc. Get that special treatment you deserve. Besides, wouldnt you rather go through a back channel than the main door?
6.) Remember that this is not only a meeting for you, its one for them as well. Be prepared to answer some of thier questions that they may have for you as well. You might want to brainstorm a little to prepare yourself.
7.) Learn some words in Chinese, like they say, 'When in Rome, do as the Romans do'. They will like you more if you learn some Chinese words and learn some of thier customs. It shows them a level of respect.
8.) Me being Vietnamese, I know about asian culture. When you do go to China, remember to be respectful, asian cultures are heavy into respect. Take off your shoes in someone's house, greet everyone (pay your respects), and if they greet you with a bow, remember to bow back. Now there is a thing to know about bowing and you may choose your action based on what I am about to say. If you return a bow, when you bow and your head is higher than theirs was, it shows dominance. If you are even, it shows neutrality. If your head is lower, is shows submission. I personally would do the submission more and maybe the neutral. The submission is submissive yes, but its a sign of respectfulness. You can do the neutral as well though and that will work as well. If you want to do the dominant bow, it could help or hurt. It could show as disrespect, especially if they are older than you, or it could show your confidence. Personally I think there are other ways to show confidence.
9.)Take pictures if they let you. As many as you can! Take pictures of them too if you want. I would:).
Anyway, this is all I can think of right now, if I think of more I will let you know. One more thing, while you enjoy yourself, remember your main goals for being there in the first place, which is to make a business contact or a few. Always be focused and on the lookout for more business opprotunities, make the best of your trip. Most importantly, Have fun!