I want players to be able to customize their character as much as possible, but generating lots of variations of hairstyles, face shapes, etc can be quite costly. I'm attempting to give a solid number of options without going crazy, hopefully there will be enough that most people are happy with their avatar.
An area where I think I found a nice solution is on the actual look of the outfits. I've decided to have a pre-determined outfit for each "sport", which the player can't change-- so the "gymnastics" outfit only has 1 shape, and overall color pattern. However, it has a space on it to display a country flag, and all of the colors of the pattern can be changed dynamically.
I then found a database of all the country flags in the world, and imported them all, running a script to generate the correct texture format I need, and also extracting the top 3 most used colors in each flag, and set those as the outfit colors to accompany that country flag. I also give you the option to "shuffle" which colors will go where on the outfit, from a total of 6 possible combinations (since there are 3 colors total per outfit).
Here is how that looks in the current build: a huge list of country flags you can select, as well as a toggle for the "color scheme" to adjust which colors end up where.