This is my workflow for UV Painting in Blender using Rebelle 7.
I like using Rebelle 7 because it mimics real media like oil paints or watercolor and pastels etc. and it has unique color mixing abilities that are similar to mixing with actual paint.
The simplest method for making the material is to add a new material to the model and add an image Texture. This can be done in the General tab.
In the UV Editing tab select all the faces that you want to paint, right click and UV Unwrap them.
Make a new image in the UV panel and save it as a PNG file.
The faces need to be selected in edit mode to reveal the UV header (below) where you can export the UV Layout to your file.
This process will leave you with something like this that you can import into your painting software. I use the “Open Image in External Editor” feature which you can set from the Preferences settings in Blender to open in Rebelle 7 automatically. I save the PNG file as a REB file so I can manipulate layers and effects from Rebelle 7.
Each component of the image is placed on it’s own layer. UV, skin, eyes, and features.
This way you can hide the UV while working in detail. I know it looks freaky but this is a quick proof of concept and demo so don’t be alarmed.
If you are wondering why the eyes have been separated it’s because they are a separate mesh of which I have selected only the visible component from the view I’m using in Blender. Obviously if you were paining a whole model you would be more selecting in your selections and do whole components together etc.
Once you have done in Rebelle 7 export the image as a PNG again (File-> Save As) and reload the image in Blender in the Texture Paint tab to see the new changes. This is the only really clunky part of the process but you get pretty efficient at it after a while.
In the UV Texture Paint tab of Blender you can paint on the image with Blender brushes and colors both on the UV image on the left and the actual model in 3D space on the right. Which is handy for placing hard to guess features like the sclera or the skin around the eyes and fine hairs. The only problem here is that any changes need to be saved into a PNG file and imported back into Rebelle 7. Working on that file means that you lose all your layering and control so I like to import it as a reference image and use that to place my marks in Rebelle 7.
This is what the base Material Node looks like in the Shading Tab. It’s very simple and the default settings are adequate for getting started.