If you're hunting for a casual and at the same time on-trend getup, wear a multi colored crew-neck sweater and blue jeans. To introduce some extra flair to your ensemble, add a pair of casual boots to the equation. So as you can see here, it's a sharp, not to mention spring-friendly, getup to have in your transitional sartorial arsenal. A fail-safe option pairing appropriate for guys in their 30s who prefer casual dressing.