Such items as a navy suit and a navy crew-neck t-shirt are the perfect way to introduce some elegance into your off-duty rotation. A pair of dark brown athletic shoes adds a more relaxed aesthetic to the look. When temps are dipping and autumn is in full swing, you'll love this outfit as your favorite for unpredictable fall weather. This ensemble shows that as a 20-something guy, you have a wide array of sartorial options.