This combo of a shirt jacket and a black and white short sleeve shirt is a winning option when you need to look casually classic in a flash. Rounding off with a pair of black leather loafers is a guaranteed way to bring a bit of zing to your outfit. Seeing as it's boiling hot outside, this outfit appears perfect and entirely summer-appropriate. As you're transitioning from your 20s to your 30s, you want to start dressing like an adult man. If that's the case, outfits like this are a surefire option.