workpermit

I have been offered a job in a company in Beijing. The thing is the people are asking me to come and work for them while they sort out my work permit. I have been offered free accommodation and all, but I am still skeptical about starting work without proper authority coz I know its risky and could cost me a lot. Is this a normal way things proceed, if so what sort of documentation should I get fro the company before I start my Visa Process ?

Thank You,