Reach for a mint print crew-neck t-shirt and black cargo pants if you want to look casually cool without much work. Rounding off with a pair of black leather casual boots is a surefire way to breathe an element of sophistication into your outfit. This combination isn't a hard one to nail and it's summer-friendly, which is most important when it's boiling hot outside. A fail-safe option outfit appropriate for gentlemen in their 20s who like casual dressing.