Just my tupppence worth: Vary rarely a PS procedure works out-of-the-box. Best thing is use it as a concept, look at the result and ways to get there in Gimp. My first try.
1. Before anything else , make sure that the stylus is set up for pressure-opacity.
2. You need Dynamics -> Pressure Opacity on for that to work. You are showing Basic / (dynamics off) as screenshot.
3. Try all the layer modes. If you hover the mouse over the 'Mode' the scroll wheel quickly cycles through the types. Burn in this case seems to work best.
4. I would keep the brush mode to 'Normal' but reduce the brush opacity to suit.
Anything else:
Have a look at the order of your layers, Fill under your outline, But add shading over the fill. For complex images consider using layer groups.
Also, have a look at the mypaint brushes, some of those good for overlays.
1. Before anything else , make sure that the stylus is set up for pressure-opacity.
2. You need Dynamics -> Pressure Opacity on for that to work. You are showing Basic / (dynamics off) as screenshot.
3. Try all the layer modes. If you hover the mouse over the 'Mode' the scroll wheel quickly cycles through the types. Burn in this case seems to work best.
4. I would keep the brush mode to 'Normal' but reduce the brush opacity to suit.
Anything else:
Have a look at the order of your layers, Fill under your outline, But add shading over the fill. For complex images consider using layer groups.
Also, have a look at the mypaint brushes, some of those good for overlays.