If you don't get Fine Woodworking magazine take yourself off to a store and buy the latest copy. It has a *great* article on furniture design that explains proportions and how to apply them better than anything I've ever seen. It is an absolute must have IMO. I'm going to make a copy to stick in my design notebook, just so it is there when I need it. What I've discovered is that my eye is pretty good. My designs that look right to me seem to fit the "ideal" mathematical model pretty closely.
Check it out.
Tim Douglass