Jama Jurabaev, a Senior Concept Artist at ILM, has released two tutorials on 3D paintings.

Jama Jurabaev, a Senior Concept Artist at ILM, has released two tutorials on 3D paintings. The guides  will show you how to create a 3d painting from scratch in Photoshop. The artist goes through basics towards more advanced stuff, giving an overview of the features of the tool and explaining some principles.

Requirements: 

• Photoshop CC 
• Octane Render (Optional)

Each tutorial includes:

• Over an hour of videos with narration
• Photoshop Files
• Actions
• BONUS: Octane files and painting demo

You can the tutorial ($12 each) here and there.