I'm trying to be non-software specific, i.e. I'll try to explain in terms applicable to all 3d packages.
Here's what I do:
I go for a map that changes based on how much light falls on it (shadow/light falloff or lighting gradient ramp) and have it control the saturation of my skin color or bitmap so that saturation is lower in the lit areas, a bit higher in the shadows and highest near the shadow border. This is to simulate light entering the lower layers of the skin in the lit areas and leaving near the shadow borders.
I'll also make the highlight color more or less pinkish because... uh .. it looks better I think.
I'll post an example later.
Usually I'll also make a procedural map to simulate freckles and pores which I unwrap and comp with my texture in photoshop for the color, bump and specularity layers.
I'm not at home ATM, but I'll add an example pic later.
BTW; I didn't come up with this stuff all by myself, it's based on tuts by Sstahlberg and others--
Note: I tried Subsurface Scattering in Vray, but I didn't have enough control and I still like my hand-hacked shader better.
Sooooo everybody....any other tricks?