Perfect the casually stylish outfit in a white and navy print crew-neck t-shirt and jeans. To infuse a more laid-back vibe into your ensemble, introduce a pair of multi colored athletic shoes to this outfit. This outfit isn't a hard one to nail and it's summer-ready, which is more important when it's blazing hot outside. Those who wonder how to wear modern casual style as you move through your adolescence, you have your answer.