The best way to organize a closet, especially a large walk-in one, is to set it up into zones according to function, based on the unique way you think about your wardrobe. For example, when you are getting dressed, do you think first in terms of occasion (work clothes, weekend clothes, evening clothes) or first by garment type (i.e. dress, suit, skirt, blouse), or first by season? Arrange your clothes with this in mind — creating a section for each category, based on the way you think. Within each section, arrange the clothes by color.
This creates a pleasing aesthetic, and makes it much easier to assemble outfits.