Now that I found the general view, I fine-tune where it will fit on my panel, so I set up my easel and line up the scene next to it, I use a brush handle to measure an imaginary rectangle whose right edge is shared with the panels left edge. At the same time I'm trying to "fix" where my eye is going to be: my viewpoint.
I'm using my mixed black to sketch almost like charcoal.
I had to move a few things before I was finished with most of the measuring, see this blog post about measuring:
I put the green in last, and they got crowded out.