Show that you do classic and casual men's style like no-one else by opting for a navy sweater vest and white jeans. To bring a bit of depth to your look, complement this outfit with navy leather loafers. Keep this look ready to go come warmer days, and we guarantee you'll save a ton of time brainstorming for an outfit on more than one morning. And if we're talking fashion for 30-year-olds, this ensemble is perfect.