So as you can see, looking sharp doesn't require that much effort. Just consider wearing a blazer and a dark brown long sleeve shirt and you'll look incredibly stylish. If you're not sure how to round off, a pair of brown leather casual boots is a wonderful option. So when summer is fading away and fall is setting in, this ensemble has a good chance of becoming your go-to. Overall, a foolproof choice if we're talking fashion tips for 20-year-old gentlemen.