Quixel have an impressive library of scanned assets available for rendering with Arnold. Below is a test render using one of their wood stump assets.

Some free HDR maps can be downloaded from the websites below:

http://www.maximeroz.com/hdri/

http://noemotionhdrs.net/index.html

https://hdrihaven.com/

http://www.noahwitchell.com/freebies/

Pingo has a collection of realistic HDR Studio Lights with some free samples available for download. These would be ideal for connecting to the color attribute of an Arnold light such as Quad or Disk to give realistic color and reflections.

An introduction with some basic concepts and explanations around OCIO config and synColor config files has been added to the MtoA (2017) user guide in the links below.

https://support.solidangle.com/display/A5AFMUG/Maya+2017

https://support.solidangle.com/display/A5AFMUG/Output

Skin shading is very simple using the Standard Surface shader in Arnold 5. From the Arnold user guide:

“When rendering skin, you would use a Radius color value like R:1.0, G:0.35, B:0.2, indicating that red should scatter deepest and green and blue less. This would replace the three layer workflow for skin where you would make the deep layer red to indicate that deep should scatter with a larger radius. Setting scatter_radius.R to a larger value would correspond to that.”

Below is a an example of such a skin shading setup (digital Emily files can be downloaded here).

Arvid Schneider has created a video that goes through the skin shading process:

Some fantastic examples of Bifrost by Igor Zanic, rendered with Arnold for Maya. Interview here.

Paolo Berto from Multiverse has some interesting tools to add complexity in Maya (with support for Arnold 5) that also includes using ABC data from Houdini (with velocity blur on varying topology). More videos here.

https://vimeo.com/219330616

Truca Team have an Arnold shader suite with over 256 shaders available for C4DtoA (using Arnold 5).

Greyscalegorilla have an Arnold playlist on Youtube. They are a useful resource even if you don’t use C4D.