Wear a white print crew-neck t-shirt and white and black vertical striped shorts if you're scouting for an outfit idea that conveys relaxed cool. Bring a more elegant twist to this ensemble by slipping into a pair of white leather low top sneakers. Casual getups for 30-something gents aren't actually that hard, as you can see here.
If you enjoy the comfort look, try pairing a white print crew-neck t-shirt with beige chinos. For maximum fashion points, add a pair of white leather low top sneakers to the equation. A cool, less conservative combo for gents in their 30s.
Wear a white print crew-neck t-shirt and grey houndstooth chinos for a bold casual and fashionable ensemble. White leather low top sneakers are a welcome complement to this outfit. This outfit should clear any doubts you had about dressing casually as a 30-something gentleman.