For a neat and relaxed outfit, choose a grey double breasted blazer and a tank — these two items work pretty good together. If you wish to easily dial up this outfit with a pair of shoes, why not add a pair of black leather chelsea boots? Ideal to show the world that you're mature enough and confident enough to hold your own in the sartorial department.
For an outfit that's pared-down but can be dressed up or down in a variety of different ways, marry a grey double breasted blazer with a tank. Feeling venturesome? Spice things up by rounding off with black leather double monks. As a 30-something, you want to start dressing like an adult. If that's the case, looks like this are perfect as inspo.