For a look that's pared-down but can be manipulated in a great deal of different ways, try teaming a navy shirt jacket with black jeans. If you wish to easily step up this outfit with a pair of shoes, complement your outfit with a pair of brown suede derby shoes. Certainly a nice pick when it comes to fashion for 30-something men.
This combination of a navy shirt jacket and grey chinos is certainly jaw-dropping, but it's very easy to recreate. For something more on the smart end to complete your ensemble, complement this ensemble with brown suede derby shoes. This combination demonstrates that dressing maturely and looking fashionable are not mutually exclusive things.