A teal shirt jacket and black chinos are absolute menswear must-haves that will integrate nicely within your current off-duty arsenal. For something more on the cool and casual end to finish your look, introduce a pair of black leather sandals to the mix. You know when it's boiling hot outside, sometimes only a neat outfit like this one can get you through the day. Wondering how to master casual outfits as you slip into your 30s? This pairing is a good illustration.