Here I used the maps provided with Vic 8.1. I think these are 4k but I'm at work right now and can't check. For now, the high resolution render brings out those microdetails like pores or wrinkles under the eye. I am not sure if they exist in the downsample.
But once I am happy with all the rest, I'm going to take the UVs of the model and project skin with micro details from TexturingXYZ. Those can be up to 16k or more depending on which one you buy. Use micronormals for pores etc and for larger details like wrinkles or potential zits etc I plan to use height maps and tessellate them. I am not a fan of the perfectly smooth and spotless Daz skin. For extra realism I'll be making vellus hair in Blender because Daz ones are hot garbage (face ones. For abdomen and back they are good and I use them in this render already).
But if you don't want to go through all this effort, the Daz 4k skin shades are good enough (the 8.1 PBR ones, I don't know how to use Iray uber shader yet).
Also keep in mind that skin is not everything. For this, I went through the spec manual of a D90 and emulated the sensor/prime lens of 85mm in the camera settings too. IGPT is a great plugin that fixes a lot of the issues with Daz camera (like DoF) and it gets you halfway there to simulate a real camera in Daz. Also for the lighting I used proper methods like diffusers, instead of the basic Iray lights and while it adds a lot to the rendering time since light has to scatter through a thin mesh and get diffused properly and THEN pass through a grid to be focused, it adds some more realism to bring it closer to what a studio setup lighting would be.
I hope this answers any questions without going too technical. If not, feel free to ask about any specifics.
