For a neat and relaxed ensemble, opt for a brown military jacket and a crew-neck t-shirt — these pieces work perfectly well together. Finishing with a pair of dark brown leather casual boots is an easy way to give a sense of class to your look. It's a good option if you're putting together a well-coordinated look for unpredictable fall weather. Wondering how to master casual dressing as you slip into your 30s? This combo is a great example.