If I may:
I'm really no expert, and lighting is something I've struggled a lot myself with. but here's my 2 cents from what I've learned.
Your scenes are too bright. Sarah's right shoulder is burnt (essentially white), and you can see a mix of white and yellow lights in the scene.
I'm not sure how light works in Daz (I find it bad, much prefer Blender!) but I would reduce the environment light. make it all a bit darker and add more contrasts (look around you in real life, even a well lit room as some darker areas).
for example, I feel like your swimming pool scene should be much darker in the background. it would also make the neon signs pop! consider adding some depth of field, always works wonders (but not too much, don't overdo it).
I assume you use 3 point lighting? if not, go google.
use softer lights (again, not sure how in Daz, but i'm sure some people here can help you), and set them up in complete darkness to get the skin looking just right, and only then add environment lights, then adjust everything accordingly.
I also like adding a tiny bit of volumetric fog (but like a ridiculously low amount, unless i want an actual foggy scene) but that's just my personal taste.
and then of course, post processing (photoshop, gimp) perform actual miracles, with just a few sliders!
the post above yours from Pillock is actually a perfect example. Compare Quinn's skin in his render to the skins in yours. see what I mean?
keep it up man, your art is looking nice!
