This is definitely a more complicated picture and pose, but I like the color balance on your latest oekaki a bit more. The shading on this one helps add a bit of extra detail to the picture.

As for grass, I think a quick little trick that might help you is to sample colors from a few areas, and draw a few blades of grass coming from the area where you took the sample from. That give the grass a fairly uniform look, and just drawing a few blades can really add to the texture.

You said that you don't mind critiques, so I suppose that you won't if I give you a somewhat in depth one.

Since one of your focuses with this picture was shading I'll stick with it. I see that you started out with a black and white image then added color. This good, as it is easier to recognize exact values when working only in black and white. One problem is that it does not seem that you go dark enough with your shading. What might work well is to use a black low opacity brush and go over the parts you want darker several times- don't be afraid of using a larger brush either. The idea is to basically be efficient with each stroke, sometimes a larger brush is better for larger areas. Highlights should be done in a similar fashion. While doing this remember that colors are more visible in grey tones- don't over do the shading and highlighting or you will kill your colors. This brings us to how to choose where the highlights and shading should go, and it will be different for each picture. This could be a very complicated topic to discuss here. light, it bounces off of surfaces, what we need to know is how. I think the easiest thing to remember is to think of a bouncy ball and how it bonces off of a surface. This is basically the way that light reacts when hitting a surface(if you neglect the acceleration due to gravity and some of the friction involved with the atmosphere, this representation becomes more accurate). So basically think of the light source of the picture as an area emitting a bunch of bouncy balls in every direction. Should the bouncy ball from the source hit a particular surface bounce off then hit the view point(camera if that helps), then that area should be made brighter. Should the bouncy ball come close to hitting the camera that area should be darker than the area that had the ball hitting the camera. The further it gets, the darker the shading. Sometimes there will be a situation where the bouncy ball will bounce off of one surface, bounce onto another surface, and then bounce to the camera. This will produce a dimmer greyish area. Also the second surface will take some of the color of the first surface. This is called radiosity. Should an area not be hit at all this area should be black, though that is not entirely realistic as there is almost always some kind of ambient lighting to keep this from happening.
As you can see from the above, it is important to have a clear idea of the forms that you are trying to render, or else you are not going to know how a bouncy ball will bounce on them. It is also important to have a clear idea where the light is coming from, sometimes it helps to draw an arrow to show where the light is coming from the strongest.
Hope this helps and was what you were looking for.