Put the paint down and leave it alone.
It's probably unrealistic to expect that any of us will paint a whole picture without trying to correct something here or there, but every great painting I've seen looks like it was done with absolute
Rex Brandt Mud Puddle
Nothing here has been scrubbed out, wiped off, blotted or otherwise disturbed. I'll stick my neck out and say this look of rightness does not come from Rex Brandt's unerring eye for perfection. It's more likely he simply knew that the strokes he made were within the range that would work just fine, and that trying to make them better would only result in making them look wrong.
Our work on skies today may have given you a sense of how this works. First of all, it is not as important as it may seem to get the strokes "perfect". Perfect enough is more like it. In other words, the range of what will work fine is probably wider than you think it is.
Clouds and shadows are very forgiving subjects, allowing a wide range of treatments that are perfect enough. But they do not respond well to fiddling. If you go back into either one to make it look more like what you intended, you will probably lose more than you gain. Instead, just put the paint down and leave it alone. look at the painting as if someone else had painted it and asked you if it seemed like a good idea to make an adjustment here or there.
If you get a chance to paint skies from life, spend some time practicing this. You can also work from photos, which are easy to find online.Googling cloud images will give you plenty to choose from. Or use one of these:
Leave some room at the bottom of the page for a landscape or a cityscape.