In the Seinfeld episode, “The Bizarro Jerry”
George is confused on what to wear for casual dress:
GEORGE: She wants me to dress smart casual. What is that?
JERRY: I don't know, but you don't have it.
GEORGE: Right. Bye.
If you’ve always interpreted "casual Friday" as "wear-anything Friday," you should reconsider.
If you usually wear a suit to work, go for a textured blazer, a white shirt and some chinos (navy or tan khakis) with leather suede chukkas. Blues and tans are great colors that work well together (e.g., a navy blue blazer with tan chinos or tan blazer with navy blue chinos). An easy and casual smart option ---- the white shirt and smarter details like the tailored chinos, say that you're just one notch below the level of formality of your normal work clothes. You likely already have these in your wardrobe, but if not --- these elements are easily found anywhere.
If you don’t have the leather suede chukkas, a pair of nice derby shoes will work fine.
Another tip, you'll want to pay extra attention to FIT. Go for slim or straight-fit trousers, blazers and shirts. This easy and "SMART CASUAL" dress tip will keep you from looking like George Costanza!
