For something more on the casually cool end, choose a navy plaid long sleeve shirt and a white crew-neck t-shirt. Clueless about how to round off this outfit? Rock a pair of black leather chelsea boots to dial it up a notch. Keep this outfit ready to go come warmer weather, and we guarantee you'll save time trying to pick out an outfit on more than one occasion. And if we're talking outfit ideas for gents over 30, this ensemble looks good on most guys.