experimental of digital painting from hayao Miyazaki

this is the recently animation movie of Hayao Miyazaki, release in this month, called 風立ちぬ, and story base on the time before and during the second world war.

those scenes really inspired me to think about the green tones, as Jordan suggested me to try on using hard brushes to make it my painting more clean and readable , i was trying to paint it more hard and not to blur.

From the past when i was in diploma course, tutors ask us to choose the painting we like and explore to enlarge the painting, to experiment the tones and structures. So i try to do that in digital as well , a i am not really know about the techniques while every time i paint and the colour will go darker and darker , the only thing i can do is using eraser to remove the dark and paint it again but that doesn't go well as the new colour will jump out next the dark colour.Would be great if someone able to give me advices about how to  techniques.