To create a casual look with a modern spin, opt for a long sleeve shirt and olive cargo pants. If you wish to effortlessly smarten up your getup with a pair of shoes, why not complement your outfit with a pair of black leather derby shoes? So if it's a baking hot summertime afternoon and you want to look seriously stylish without putting in too much work, this look will do the job in no time flat. Those wondering how to wear semi-casual outfits as a teenager, you have your answer.