Why not wear a denim jacket and a white and blue short sleeve shirt? Both of these pieces are super practical and look awesome together. A great pair of black leather tassel loafers is the most effective way to power up this ensemble. During the colder months, when warmth is above all, it can be easy to surrender to a less-than-stylish ensemble in the name of functionality. This ensemble, however, is a vivid example that you totally can stay snug and remain stylish at the same time in the colder months. Now that's how you do semi-formal as a gent in his thirties.