If the setting allows a relaxed casual getup, try pairing a black fair isle crew-neck sweater with black chinos. Make this ensemble slightly sleeker by rounding off with a pair of black leather derby shoes. Seeing as it is getting chillier every day, this outfit seems a viable idea for in between seasons. Take cues from outfits like this if it's time to add more gravitas to your 20-year-old's wardrobe.