I was fraustrated for the longest time with my skill has a painter in Sketchbook Pro. But thanks to this tutorial [robaato.deviantart.com/art/Pro… I think I finnaly got it.
Unfortunatelly, I was so unsure of how it would come up that I even forgot to record a time-lapse video... But here's a description: I used the copic color selection just to splash the main colors then used a wide airbrush for the highlights, then worked on the light and shadow, and them twiked a bit with the smudge to give that 'painting' look. In the end, I added a second highlight with a smaller airbrush, just to contrast the color of her hair, and corrected values and saturation on a photo app. I must admit that this is probably the first time I am really glad with the end result...of course, having a really good drawing to start with did help. Thanks Mr. robato-San!
Drawing by Robaato
Colors by Me