A blazer and a dark green long sleeve t-shirt combined together are a perfect match. Take a classic approach with shoes and complete your outfit with a pair of navy leather tassel loafers. As a 30-year-old guy, you want to start dressing like an adult. In this case, inspo like this comes in handy.
A blazer and a dark green long sleeve t-shirt are absolute menswear staples that will integrate really well within your current casual collection. You can take a more sophisticated approach with shoes and complement your look with brown leather oxford shoes. As a 30-something gentleman, you want to start dressing more like a mature gentleman. That's when ensembles like this are a safe bet.
If the setting calls for an effortlessly sleek look, you can always rely on a blazer and a dark green long sleeve t-shirt. As a 30-something gentleman, you're sure to like this combination.