If you feel more confident in functional clothes, you'll appreciate this laid-back pairing of a navy long sleeve shirt and navy chinos. Give a dressed-down twist to an otherwise mostly dressed-up getup by finishing with a pair of navy suede low top sneakers. Undoubtedly, it's easier to work through a roasting hot day in a easy and breezy combination like this. When it comes to casual dressing ideas for 30-something Millennial men, this combo looks good on almost any gent.