Full disclosure: Ray edited my work when I wrote for WotC.
That said, I got spoiled by his input (and learned a great from it). This guide provides a great deal of his insight directly to writers. As he points out, Ray didn't write THE definitive style guide, but focused on the areas that he frequently sees when editing gaming material. Many authors setting out to make a name in the RPG/tabletop publishing realm bemoan the fact that they cannot afford an editor. In the earliest days of your career that can be true. But you CAN afford to pick up Ray's advise and I highly recommend you do.
[5 of 5 Stars!]