The key is to make sure the colors contrast. Her black textured pencil skirt (love the tiers of material) contrasts with her brown shoes that are a light tan, keeping the outfit springy and charming. A simple white shirt under her cardigan was a great choice to keep it simple and let the necklace do more of the work!
Did I mention the necklace? Turquoise, tortoise shell, and diamonds...who doesn't love that combination! It adds another hint of color while staying within the same tones and the rest of her outfit.