A dark brown shirt jacket and khaki chinos are absolute mainstays if you're picking out a semi-casual wardrobe that matches up to the highest menswear standards. Kick up the classiness of your look a bit by wearing dark brown suede derby shoes. This ensemble should prompt anyone who wasn't sure about dressier outfits as a teenage guy.
As you can see, it doesn't take that much work for a man to look effortlessly smart. Just consider wearing a dark brown shirt jacket and khaki chinos and you'll look incredibly stylish. For a more casual take, why not add black and white canvas low top sneakers to the mix? Those who wonder how to rock cool casual dressing as you make your way through your teens, you have your answer.