A yellow knit blazer and khaki chinos are absolute mainstays if you're planning a classic and casual wardrobe that matches up to the highest menswear standards. Kick up the appeal of this ensemble by slipping into a pair of athletic shoes. You're sure to always look good even despite the oppressive heat if you have this look as a last-minute grab. This combination demonstrates that stepping into your 30s is no reason to shed casual style altogether.