Well, I've never been, but I did very much enjoy watching "
Eating in Canton" (available on Netflix
here). Probably not very many specific tips, but at least it ought to get you in the mood. It has the feel of a charmingly inept (but enthusiastic!) Tourism Bureau video. (And FYI, there are more in the series-- one about tofu, another about Peking duck....)
I'm sure I'm not alone in saying, Have fun, and tell us all about it when you get back!