When it comes to timeless sophistication, this combo of a navy double breasted blazer and a white long sleeve shirt is the ultimate look. A cool pair of dark brown suede tassel loafers is the most effective way to upgrade this ensemble. So if it's a baking hot summer day and you want to look seriously stylish without putting too much effort, this look will do the job in no time flat. And if we're talking casual dressing ideas for 30-year-old gentlemen, this getup is ideal.