Geoff,
Like Kevin, I have only a vague idea about Taguchi's work. What little I did know has faded into the dim past but, from what I remember, it is not simple and there is no simple way to deal with it. You may have seen the discussions about 6 Sigma and noted how, out of ten people you can get ten different ideas about what it is supposed to be. Now Taguchi, I would say, was a very clever and experienced person who knew just about everything that had been written about variables. Some of it is sure to be pretty difficult for the layman but, Taguchi, having absorbed all that stuff, rolled it over in his mind for years, and teased it and worried it until he came up with a new way of looking at it. If we can't agree about 6 Sigma, what chance have we with Taguchi unless we begin with an understanding of the theory and thought process that led him to his conclusions?
I suggest you start by reading anything you can get hold of that relates to Taguchi's work. Then, having identified the areas where your knowledge isn't sufficient to take you on, go back and pick up the knowledge you need.
The worst thing you can do is drive on with a smattering of knowledge and expect to achieve anything useful. Most people can draw wrong conclusions from a histogram.
rgds, John C