First of all, to be able to get decent results with Vray SSS your scene needs to be carefully set. Make sure that your units are set to centimeters. Then you can measure your model and see if it is scaled properly. If not, try scaling it before you start working on your SSS shader. Also after you decide what kind of lighting you will have in your scene make sure your camera's ISO, shutter speed and F-number are set to the proper values. Otherwise your light's intensity might not be enough (or too much), but your camera might show everything properly except SSS. I ran into this problem when I was trying to adjust the SSS; it took me a while to figure out the problem was the camera settings not the SSS.
For the subsurface scattering shader I again used a VrayBlendMtl in Additive mode (Fig.11). The reason for that is because I could not get decent specs with SSS specs. So I used a VrayMtl to get the specs instead. I created the VrayMtl for the specs and a Vray Fast SSS to get the color and the scattering and blended them in VrayBlend Mtl (Fig.12).
Fig. 12 - Click to Enlarge
The good thing about Vray SSS is it has presets that make sense. I started with a preset and tweaked it for a while and also tweaked my texture maps in Photoshop and got decent results in the end. Again, if your scale, lights and camera are set properly, and if you do not have any problems in your mesh, you can start with a preset and get some good results in no time.
Lighting and Rendering
When I started lighting, the first thing I made sure was to set up V-Ray for linear workflow. Then after experimenting for a while I ended up using four V-Ray rectangular lights to light the scene (Fig.13). V-Ray lights are pretty straight forward and work pretty well by default, so I did not really tweak them that much. I mostly worked on the light color and intensity. I used temperature for the color mode in three of my lights, which are key, fill and bounce. Since the rim light has a high intensity, I wanted to give it a little more color so I did not use color temperature for this instance. The planks on the floor are lit by the rim light only. The spotlight effect was created by texturing.
When I felt comfortable with everything I started working on the fuzz for the clothing and the legs. For that I created a separate scene with the same V-Ray and lighting setup. Then I selected the surfaces I wanted to grow hair from. Using Shave & Haircut I quickly adjusted the look of the fuzz. One thing I also did was create a black hole shader to mask out the areas that were not visible to the camera and apply the shader to the surfaces that I grew the hair from.
When the fuzz was rendered I added it on top of the base render I got from V-Ray. I adjusted the backdrop, adding a smooth purple gradient to compliment the green chair and make the character pop out of the image a little more.
I added the smoke effect and hair in Photoshop too. I found some high resolution smoke and hair images and painted on top of those to get the desired effect (Fig.14).
Fig. 14 - Click to Enlarge
These are more or less the steps I used to create this image (Fig.15). I've tried to answer the questions I was asked about Grandma and I would like to thank everyone that gave me feedback during and after the creation. I hope this tutorial is useful and I hope you can use the tips and tricks I covered in your workflow. Thanks for reading!