It is simply a lot of try & error to get the right effect.
Arnold and Vray have totally different shader concepts and settings.
A few tips:
First, you need very good quality maps that are large enough ( I prefer now 8K maps), otherwise your skin results will lack the 'real skin' look, no matter what your shader settings are.
Then, your model scale must be in real size.
The right SSS-Prepass rate-setting is crucial for the result. I use 0 in most cases.
I also never touch the SSS-scale setting as my model has already the right size, I leave it at 1.
From my long-year attempts, choosing the right scatter color along with the matching scatter radius and phase function
is what produces all the magic in Vray.
I tried it for several years again and again, endlessly, until I found the right values for them. In the past, I also used complicated constructed scatter- weight maps and scatter-color maps etc, but you don't really need that for good results.
Especially the scatter-color is very important.
Only Vlado might know why, but the color-settings there do not only affect the color of the backscatter-effect, but also the total amount of the whole SSS-effect.
It is like juggling with 10 motor-saws. A slightly false set value there and all is gone.
Can really be veeeery frustrating, I assure you.
Also essential is the right specular-shading.
In Arnold, you can use the SSS and specs in one shader.
In Vray, it never produced satisfying results for me.
I think it's because Vray's SSS is not primarily designed for skin shading.
No matter what I tried, it always looked odd when I used the specs inside the SSS-shader (A note: VrayforC4D's VrayAdvanced-Material is different to the Vray-Max or -Maya versions)
So I do my specs in a separate shader.
Then choose 'Simple' for Single Scatter and 16 as Single scatter Subdivs, Prepass LOD is 4 and Prepass Blur is 1.2 .
I only use one or two color maps (in C4D we have a 'filter' that enables us to color-tweak, saturate etc. any basic color texture) and that's it.
Sounds simple, but took me a few years to fiddle that out.
Vray has too many settings that all has to match for getting it right.
Arnold is much easier to handle.
But it also needs some days to get the right settings (and I can tell, my settings are much different to the ones Lee has written in his Arnold-skin tutorial
So, there is really no secret sauce, but both renderers need a lot of try & error to get the right skin look.
Again, without really good color maps, you will never get really good looking skin, no matter how right your settings are.