I began to see that she often had a light background with shapes on top but the background had many, many subtle shades of color and texture. Then more definite shapes were painted on top of those.
Her paint dribbled down the canvas to create those interesting vertical lines. My attempt was done with the edge of a piece of matbard to give an illusion of dribbles.
I am trying one on my own now but it is not finished and it might never be satisfactory but the exercise was worth it!