As you can see here, it doesn't take that much work for a man to look casually sleek. Dress in an aquamarine puffer jacket and a navy blazer and be sure you'll look amazing. Brown suede desert boots will bring a playful touch to this look. As a 30-something Millennial guy, you probably want to start dressing in a more sophisticated manner. In this case, combos like this are a goofproof option.