Marrying a navy denim jacket with a black and white horizontal striped crew-neck t-shirt is a smart pick for a cool and casual ensemble. If not sure about the footwear, go with black and white canvas low top sneakers. Keep this getup in your head come spring, and we guarantee you'll save a lot of time getting ready on more than one morning. Those who wonder how to wear cool casual dressing as you make it through your 20s, this combo should answer your question.