I seem to have a three step process for fixing a painting. First, I have to figure out what is wrong with it. Often, I don't know what the problem is, but just have a nagging feeling that it isn't quite right.
I usually will leave it for a few days and let it dry while I look at it occasionally to see if it hits me. I can always see what is wrong with other people's paintings! I should be able to see it just as easily on my own. With a few days space between actually painting it and looking at it again, it often does jump out at me. I also find that photographing it makes it more obvious, looking at it on the computer screen. Looking at it in the mirror sometimes does it, but for me, a photograph is better.
Once I realize what the issue is, I have to decide how to fix it. That often takes me time. I am a relative newbie to painting, and still have lots to learn. I often work it out at night, thinking about the painting when I should be sleeping. The problem I had with the painting above is that the mountain goat and the background were the same value, and they blended in with each other. I could have lightened the goat, but on his shady side, he really was quite dark, even though he was white. I could have darkened the grasses around him, but then it wouldn't have looked like the summer tundra he was munching on. I finally realized at about 2am one night that color temperature rather than value was the way to do it. The grasses had been yellow green and I had used an orange toned board so some of the background warmth was coming through. All I needed to do was cool down the green by adding blue to it and suddenly the warmer, sunny side of the mountain goat popped out. Where he was shaded, I had to still keep the green warmer.
This whole painting was an experiment and was just done as a study to see if I could paint an animal and get the drawing right (not my strong point) and it was nice to be able to work out some of the other issues as well. I still wonder if the pile of rocks isn't too strong, but there aren't many darks in this painting, so I left them.