If you never have experience with Chinese company, and certainly one time trip to China is not helpful.
There are many way to verify a company in China, answers already mentioned few of them, and also good to get a Chinese to help you communicate with Chinese in China especially in the start point.
As many people said it is big different from Europe to do business in China. Recently I got few phone calls from China, they are import products from Netherlands, and they also feel it is difficult communicate with Dutch people, they ask me to be the middleman.
In your case, one tip for you, do not get exciting by the price and the layout of the sheet they sent to you at the beginning, most of them are fake, get a Chinese you trust to help you negotiate with China will make the start much easier.