This off-duty pairing of a short sleeve shirt and a grey crew-neck t-shirt is extremely easy to pull together in next to no time, helping you look seriously stylish and ready for anything without spending a ton of time going through your closet. Get a little creative on the shoe front and polish up your ensemble by finishing with a pair of dark brown leather casual boots. Keep this getup in your front hall wardrobe come spring, and rest assured, you'll save time getting dressed on more than one morning. When it comes to casual style for guys in their 30s, this combination looks nice on most.