Pairing a navy waistcoat with navy jeans is an on-point option for a casual and cool ensemble. If you wish to effortlessly rev up this outfit with shoes, add a pair of dark brown leather loafers to your outfit. Come hot sunny days you want to feel comfy and seriously stylish –– this ensemble is just what you need. Gents who are curious how to sport modern casual dressing as you go into your 30s, you have your answer.