For the foreground snow I had a plan. This landscape scene is from my backyard right after last December's snow storm. With wonderful reference in hand, I worked on the right side shadow snow first, then added its highlights. So far, so good.
For the left hand snow, my reference photos had this really cool pattern and I painted it with some modifications.
Hmm. It didn't work at all. That might be the way the snow was, but it was totally wrong for the painting. Also, the sunlit snow in the center needed some changes.
Here is where some creativity and knowledge can make a difference in a painting. I have already changed some details, positions, and colors in the trees. While the trees are main characters in the painting, if the snow did not "read" well, the painting would not be as successful.
Time to take a step back. First I position my chair 10 feet away and sit and look at the painting. After painting for many years I have an inkling of what can work in a painting. Searching my memories of walks in my woods in deep snow, I try and feel its depth, the cold, the sparkles on the snow's surface.
Numerous times I'll close my eyes, then look at the painting, then close my eyes.
This time it was about 10 minutes later and I was ready to grab the brushes and go for it (without looking at my reference photos.)