The slot structure I decided on for the MMORPG is a simplified one. It has only 6 slots: Footwear, Undergarment, Overgarmant, Hat, and Veil. The base undergarment is a shirt and pant set in crepe cotton with a turtleneck and bell sleeves and legs. Then there's a variant on this base: the sleeve and legs are all tied closed at wrist and ankle. And another variant: The legs are closed at the knee so they can be tucked into boots. Note that these are all the same garment, just worn in different modes. Now there's a different base garment: of the same general shape so it is interchangable with the first, but this one is made of a flat fabric, not wrinkled, and has the sleeves and legs wrapped like a dhoti (Indian pants). Obviously this one will also need a version with knee-length pants so it can be worn with boots. And a third base garment: a skintight shirt and pants set made from the model's skin, with only cuffs and a collar added. Oh, and there are also male and female versions of all these base clothing sets, so any character can wear them.
So all of those variants go in the base clothing slot. These can be worn without an overgarment, or there are several kinds of overclothing, each of which can be worn with any base: 2 kinds of robe, an x mantle, a soldier's uniform, an officer's uniform, and some capes and cloaks. I may add an apron later. For overclothing, it comes in a full range of colors like the underclothing, but each piece of over clothing also has one or more textures available for it (a texture consisting of an embroidered or embossed design, or a color pattern like a gradient fill or stripes.) Fortunately making those is the texture artist's job, not mine. ;)
Anyway, the goal is that the game's engine can look at any charater's 6 clothing slots, see which items they have equipped and what color/texture each has, and generate a stylish-looking character on the spot. Again, fortunately making this work is not my job, but hopefully my careful design has laid the groundwork that will save the 3-d modeller and clothing display programmer a lot of work and headaches.
This concludes my little talk about designing clothing concepts unless anyone has any questions or requests for additional information. :)