In Photoshop, I used the basic render pass as the base and started applying the shadow passes. I used them as both shadow and light information, so one set was with Multiply and very low opacity, and the other was with Screen or Soft Light.
The next step was to give it some SSS, so I just filled a layer with a dark red color, used the SSS pass as a layer mask and gave the layer very low opacity on Overlay to give it that subtle reddish translucency near the edges.
Remember that most of the character's clothes didn't have SSS, so I used the masks pass to mask out parts I didn't want SSS on. I prefer this method over making materials with actual SSS, especially when you're on a tight schedule. However, it might not always work well and in that case, it's better to make a decent skin material.
Next came the specular passes. I just placed all the layers on Screen mode and gave them all very low opacity. It was at this time that I looked at some reference because it would have been very easy to overdo it. I just exaggerated a bit in the rim light because I was going for a more pin-up style of render.
Then I used the AO pass with Multiply to enhance some of the volumes of the model, followed by the cavity pass with some Level adjustments so I didn't darken the image too much. I used it with Multiply mode to make those details pop out. Again, I used low opacity, as I find it's easy to overdo it.
For Nina, I also ended up using the SSS pass as a mask for another lighting layer (a light blue-filled layer) to give her a more ethereal look.
At this stage I also repeated some specular layers for some specific SubTools, such as the tiara and the gems in her dress, using the masks I'd done.
Some Levels, saturation and color adjustments later, I ended up with this image.
Post-production was almost complete
After this I just kept on adjusting small things and putting detail where it was needed.
For the floor, I used gradients and some painting to give it a sense of depth, and blurred the floor shadow I took from the main shadow pass.
All this process tends to over saturate the reds, so I just used a Cooling filter to balance the shadows a bit.
Finally I just used a Lens Blur using the ZDepth pass to get that nice DOF effect on the image, added a bit of noise and called it a day.
I hope you enjoyed and took something out of this. All this resulted from a fair bit of experimentation and was mostly a learning process. This might not be the best method for rendering in ZBrush out there, but it worked well for me when I was close to the deadline.
Anyway, they say the Devil's in the details and that holds true in both ways. It can be what makes an image and what wrecks it, if unbalanced. Probably the main lesson I took from this experience was to take my time in the gesture and proportions, and to not overdo details for the sake of both aesthetic coherence and time.