This combination of a navy turtleneck and navy chinos is on the casual side yet it's also dapper and seriously stylish. You can get a little creative on the shoe front and dial down this ensemble by rounding off with tan print canvas low top sneakers. This one is a great pick if you're putting together a well-coordinated ensemble for unpredictable fall weather. This combo is probably what you're looking for as a 20-year-old guy.