Consider pairing a navy plaid long sleeve shirt with a white crew-neck t-shirt if you wish to look cool and casual without spending too much time. Bump up this whole outfit by finishing with a pair of black leather chelsea boots. So so as you can see, it's a cool, not to mention season-appropriate, outfit to have in your transitional rotation. That's the style for a guy in his thirties to portray you've got what it takes to succeed.