If you're on the lookout for a relaxed but also sharp look, make an olive crew-neck t-shirt and dark brown chinos your outfit choice. A pair of low top sneakers will tie your whole outfit together. So if you're on the lookout for an outfit that's stylish but also entirely season-appropriate, this one fits the task well. Pay attention to looks like this if it's time to add seriousness to your 20-year-old's look.