Why not wear a light blue short sleeve shirt and white chinos? Both items are totally practical and will look good worn together. On the footwear front, this ensemble pairs really well with desert boots. If you're often not sure how to dress as a 20-year-old gentleman, this pairing is a perfect example.
A light blue short sleeve shirt and white jeans are amazing menswear must-haves that will integrate well within your daily arsenal. In the shoe department, go for something on the more elegant end of the spectrum and finish off this getup with desert boots. Ideal to show people that even as a gentleman in his 20s you're confident enough to make your own sartorial choices.