Consider wearing a crew-neck t-shirt and navy sweatpants for a stylish and easy-going outfit. To give your overall look a classier aesthetic, why not introduce white low top sneakers to your ensemble? In winter, when warmth is top priority, it can be easy to surrender to a less-than-stylish outfit. However, this outfit is a shining example that you totally can stay comfy and remain equally stylish in winter. When it comes to casual style tips for gentlemen in their 30s, this look suits almost any gent.