As I Mentioned In The Last Post...

...I use the razor to cut in details and shapes. Here, I am making space for clouds in the pretty gradient created by a low sun. 

I paint in the clouds, smoothing and blending them into the sky already painted.

Then once they have been painted in, I cut in the singular blades of grass. This way, when the grass is later painted in, the surface stays smooth and pictorially unified. 

In other words, it is one picture plane and not looking like they are pasted on top of what is painted behind them, in this case the sky.