The go-to for a cool and casually classy getup? A brown plaid blazer with a white long sleeve shirt. Go ahead and complete your look with a pair of brown leather double monks for a sense of refinement. If you're looking to keep warm this winter and look seriously stylish while doing so, this getup is for you. Those who wonder how to wear semi-casual style as you make your way through your 20s, you have your answer.