One thing that well dressed men have in common is a well developed sense of restraint. Take my friend Matt, for example. He wears clothes with a Neapolitan cut, and combines them with shoes that are too informal and too light in color to be appropriate by English standards. But the combinations work on him, and the reason is his restraint.
You see, when Matt dons an aggressively colored pair of shoes, he typically combines them with a solid colored suit, a shirt with a simple pattern and a conservative necktie. He'll show no more than a quarter inch of plain white pocket square. Instead of being supporting elements for the kind of ensemble you might find on Domenico Vacca, for example, where everything is often a bit short, or tight, colorful or otherwise noticeable, the shoes blend in. That's restraint.
I think restraint may be the most difficult thing to learn about dress because there's such a fine line between too loud and too boring. Clothes have to have a bit of color and cut or they're too dull. They have to have pattern, but get the combination wrong and suddenly they are too loud.
The boater hat on the man in the illustration would probably be over the top worn with a brighter necktie, patterned waistcoat and chestnut shoes the way you might see it on Mr. Vacca. But the hat band is bringing most of the color to the man's clothes and in that restrained context, it works. I don't think Matt would wear it though. He's not a hat guy.