This combo of a dark brown windbreaker and khaki jeans is a safe bet for an effortlessly cool outfit. Dark brown leather casual boots are guaranteed to infuse an extra touch of sophistication into your outfit. As you can see here, it's very easy to look amazing and stay toasty when chillier weather comes, all thanks to ensembles like this. As you can see, as a 30-something Millennial gentleman, you have a wide range of dressing options.