I'm posting these updates a bit later than I intended, but I wanted to show some progress!
In general, I tend to bounce between Zbrush and Maya pretty frequently to create my models. For example, this hat started as a roughed-out shape in Zbrush, but I felt I could get it closer to the look I wanted by sending it over to Maya to create cleaner topology. In this situation, this cleaned up model can serve as both my low poly, and high poly models.
The image on the left is the Zbrush block out, with the retopologized model on the right:
75% of original size (was 674x19) - Click to enlarge
I am also developing her clothing by making extractions from the CC base mesh. I am trying to keep the topology pretty close to the CC base mesh, so I can get a nice transfer of weights when the outfit gets imported into CC.
For example, here is the topology I extracted and then modified for her skirt:
75% of original size (was 674x19) - Click to enlarge
Similar idea with her shirt:
75% of original size (was 674x19) - Click to enlarge