For a tested casual option, you can rely on this pairing of a beige crew-neck t-shirt and shorts. If you need to immediately amp up your look with a pair of shoes, add a pair of black slip-on sneakers to the mix. Casual getups for stylish gentlemen in their 20s aren't actually that hard, as you see.
If you gravitate towards comfort dressing, why not test drive this combination of a multi colored tie-dye crew-neck t-shirt and shorts? Black slip-on sneakers will give a strong and masculine feel to any outfit. This combo demonstrates that in your twenties your sartorial options are in no way limited.