So as you can see, looking casually sleek doesn't require that much effort. Just pair a harrington jacket with a polo neck sweater and you'll look awesome. To infuse a mellow feel into your outfit, complete your look with a pair of navy and white canvas low top sneakers. As you're transitioning from a kid to a teenager, you probably want to start dressing more like a grown-up. In this case, looks like this prove useful as a source of inspiration.