The Biggest Mistakes poser users make when trying to create a "cell" Styled renders is to take complex models with complex bitmap textures & trans maps and lighting setups and convert them into cartoon style renders  as is.

frankly for cell render the textures especially need to be very basic
for example this is the Old Zygote "Stylized businessman'
he has basic flat flesh colored skin and basic flat colors on his clothing
he therefore  "cell shades" very well in Cinema4D toon render.

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