This cool and casual outfit is really pared down: a white crew-neck t-shirt and grey chinos. If you're on the fence about how to finish off, a pair of beige slip-on sneakers is a tested option. When temps are starting to drop and fall is in full swing, you'll love this getup as your go-to for unpredictable fall weather. Wondering how to nail casual looks as you make your way through your 20s? This combo is the perfect answer.