If you like functional style, try pairing a dress shirt with blue ripped jeans. The whole look comes together perfectly if you introduce a pair of low top sneakers to the equation. Laid-back combinations for gents in their 30s aren't actually that hard, as you see here.
This combination of a dress shirt and black chinos is solid proof that a safe ensemble doesn't have to be boring. Does this ensemble feel all-too-polished? Let low top sneakers mix things up a bit. This getup illustrates that in your thirties your dressing options are looking good.