Use your local Chinese embassy as a starting point. I remember seeing a Chinese government website devoted to this but I cant remember the name.
Find the company names first and make a contact first, asking permission to visit. Don't just show up. Also ask if they offer a translation service or know of one.
Asians can be incredibly accommodating and don't be surprised if some of your trip gets comped if they feel you are serious about doing business with them. Ask for samples or at least a very good price on samples.
Don't say, you are going to be visiting a lot of businesses. Make it seem you are there for them, unless of course they ask. DO as much research as you can so you know something about the company. Learn things about them that they might not expect you to know. Imagine if you owned a business here in the states and an Asian were visiting you to do business and they asked if the new machines you recently bought were improving production. You would be impressed right? Especially from a foreigner.