This casual combination of a red plaid shirt jacket and navy jeans is super easy to put together without a second thought, helping you look dapper and prepared for anything without spending a ton of time digging through your wardrobe. Finishing off with navy canvas low top sneakers is a guaranteed way to infuse a more laid-back vibe into this outfit. With rising temperatures come warmer days and the need for a summery look just like this one. Now that's how you dress casually as a 30-something guy.