The Last Tree

I am working on this project for Color Theory at the Art Institute and I have been thoroughly enjoying this project. What I did was model the tree and ground and branches and everything in Blender, including rendering the stars and placing a couple of spheres. Now I am going through and painting the ground and the stars with MyPaint to get a good feel. I am having a bit of trouble rounding out the ground and making it look realistic and having the shooting stars look believable. The thing is. They need to be some sort of red because I am practicing Goerthe’s Color Proportion Theory. Could anyone give me some tips on how I can make this look a little bit better, this is my first adventure into the realm of digital painting and I never did much painting in the first place. I am using a Blend and Paint brush.