This combo of a field jacket and a grey waistcoat is a safe option when you need to look like a true expert in men's style. To infuse a more laid-back feel into your ensemble, complement your outfit with a pair of beige athletic shoes. This outfit is also perfect if you're on a mission for warm weather wear to get through a slow day. A look like this will help any 30-something Millennial gentleman outshine his pals.