Good shoes are no good if they aren't a good fit. Everyone knows that, of course, but most people have at least once bought a fine pair of footwear only to consign it to a cupboard because wearing the shoes was just too painful.
So it pays to know how to determine a proper fit -- or, if you're particularly well-heeled, to have them custom-made.
The golden rule with ready-made shoes is to try them out -- and not just try them on -- before you buy. A brief walk on hard flooring is ideal.