I’ll admit it — my mom’s over 50 and has better style than me. There, I said it. Somehow, she always manages to look effortlessly put-together, even when she’s just running to the grocery store.

When it comes to fashion, it can be hard to find your groove in each emerging decade—the silhouettes that worked in your 20s might not feel like the right fit in your 50s. However, designers are ...