When you paint a sky, remember that in the finished painting the sky will not be the only thing on the page. With all the other stuff in place the sky need not be perfect, or even accurate. Try wetting the paper to a sheen, and approximating the shapes and values. The job for today is to find out how forgiving the sky is as a subject. Instead of getting wrapped up in correcting, let it be and see if it was ok after all.
Bring in all your attempts, especially the flops.