Go for a pared down but polished outfit by wearing a suit and a navy henley shirt. For something more on the smart side to round off your outfit, introduce a pair of white canvas oxford shoes to the equation. This ensemble is most probably what you've been looking for as a 30-something gentleman.
For a smart casual menswear style, try pairing a suit with a navy henley shirt — these pieces play pretty good together. To add a little flair to this ensemble, complete your ensemble with black suede tassel loafers. If you're often not sure how to dress your age but also look fashionable, this pairing is a practical illustration.