Marrying a green sweater vest and a crew-neck t-shirt is a fail-safe way to inject personality into your closet. If you're on the fence about how to finish, complete your look with a pair of dark brown leather desert boots. As you can see, this outfit is a really great option, especially for summer-to-fall weather, when the temperature is starting to drop. When it comes to casual fashion for middle-aged guys, this combo looks great on most guys.