Wear a navy and green vertical striped blazer and navy jeans for a sharp, laid-back ensemble. Black leather tassel loafers will infuse an added touch of refinement into an otherwise standard look. If it's one of those gloomy fall afternoons, what better to brighten things up than a seriously stylish outfit like this one? All in all, a fail-safe choice if we're talking dressing ideas for guys in their 40s.