If you’re a jeans-and-a-tee kind of guy, you'll like the simple yet casually cool pairing of a white and navy horizontal striped crew-neck t-shirt and black jeans. And if you wish to immediately smarten up your look with a pair of shoes, why not add a pair of brown leather casual boots to your getup? You can take inspiration from combinations like this if you're in your 30s and you want to take a more mature approach to your personal style.