Excellent tutorial ! / Saving image textures and choosing paint colors
Thank you very much for this excellent tutorial 😀! Your layer technique also works with 2.79 (tried it just out of curiosity 😉), just some differences in the shortcuts and new image textures can't be created directly from the "Image Texture" node.
Finally just two short hints:
1) One could think that the color for a certain layer is selected in the dialogue for the image texture creation and that this color and a certain image texture are automatically chosen by clicking on a specific texture layer node group. But the color from the image texture creation is irrelevant since it is set to full transparency (alpha value = 0) and the paint color is selected in the color wheel of the texture paint editor ("Tool" tab in the "Texture Paint" editor's properties panel => "Brush" => "Color Picker") . In the video, the selected colour changes with the fading in just before the texture painting begins. Furthermore the texture image you're painting on is chosen in the "Tool" tab's "Texture Slots" panel.
2) Don't forget to save the edited texture images ("Image Editor" => "Image" => "Save all images") before saving the file and closing Blender!