For comfort dressing with a fashionable spin, you can rely on a grey crew-neck t-shirt and tobacco chinos. Puzzled as to how to complete this outfit? Rock dark brown leather casual boots to amp up the fashion factor. Needless to say, it's easier to work through a blazing hot day in a easy and breezy getup such as this one. And if we're talking casual dressing ideas for 30-year-old guys, this combination is perfect.