Wear a white and red and navy short sleeve shirt and chinos if you want to look neat and relaxed without too much effort. Complete this outfit with a pair of brown leather desert boots and ta-da: this ensemble is complete. As a man in his thirties, you probably want to start dressing like an adult. In this case, looks like this are perfect as inspiration.
If you're on the hunt for a casual but also on-trend outfit, marry a white and red and navy short sleeve shirt with chinos. For something more on the casually cool side to finish this outfit, introduce a pair of white athletic shoes to the mix. And if we're talking casual fashion tips for 30-something gents, this combination is a good look on almost any gent.