Painting a painting, Lyell Canyon

Starting a new painting can be a little nerve-wracking, no matter how many times I've done it before.  I have a photograph I'd like to render, a blank canvas, some paints, and a general idea of the way I'd like it to look.  I assume that if I flail the paints in the direction of the canvas for some number of hours, it will eventually start to look the way I envision, but the process can be an exercise in fits and starts.  Below, I've recorded my progress on my most recent painting, an acrylic of Lyell Canyon in Yosemite, from my hiking trip on the John Muir Trail.  I took a picture after I finished each painting session, most of which last about 1-2 hours (I've averaged to 1.5 hours each).