Adding the tree and more
The painting finally spoke to me and said it needed this foreground tree. It breaks up the symmetry of the driveway and foreground lawn shapes, see Step 9. Adding a vertical not only cuts the shapes into more artistic areas, but also enables me to gracefully add some leaves and branches in front of some less important areas of the house. The focus is on the front of the house.
I like the feeling of distance that the foreground tree gives the painting, as I had in my original sketch, see Step 2. I roughed in the tree trunk and some basic limbs, refined the trunk, and added the ivy border along the driveway with the cobblestones on the farside. On the porch, I added planters, though I haven't put anything in them yet. I resolved the driveway and foreground grass with dancing shadow patterns, adding sparkle to the painting.