I did a lot of that today. My seam ripper was my most used tool today.
The sky in that piece bothered me a little, but I haven't been able to put my finger on just what I didn't like about it. Today I realized that all those scallop-y lines seemed a bit chaotic, so having finished one cloud portion, I picked all the stitching out.
I scratched my head for awhile, then decided that curved lines that didn't so much echo the cloud shapes as fill them might work better. So I started filling those shapes with a pattern of curved lines. Can you see it here?
Much better in my opinion. I'm not quite sure why this works so much better (at least to my eye) than the first scheme, but it does. I think I have made a discovery, but I'm unclear about what it is!
In case what I am describing is not clear in the photos, here is what I started doing:
had this problem once before. Cutting a little cardboard template had worked well, and it worked again today.