I'd say I focus the most on hairstyles and wardrobe, especially when it comes to accessories! Almost all of my characters have an important item (jewelry, hair piece, etc.) and specific color palettes that I think show off their personality.

Meiren & Yueying are probs the clearest example. Meiren is the older sibling, but she wears simpler outfits with light, washed out colors while Yueying is bolder and more extravagant to contrast her vibrant feathers & this is partially because of how they were treated/socialized by their parents