Consider pairing a long sleeve shirt with khaki jeans for both on-trend and easy-to-style ensemble. And if you need to immediately ramp up this ensemble with one single item, add a pair of black leather casual boots to your outfit. We recommend this one if you're looking for an ultra-warm look that's as stylish as it is comfortable. This outfit proves that as a 20-year-old man, you have a vast array of dressing options.