The tree I'd visualized painting wasn't any specific tree, but something from my imagination based on my studies of trees for other paintings. Essentially: a large tree trunk tapering towards the top where it then divides into a few branches.
I placed the trunk towards the left rather than the middle, following the Rule of Thirds. One of the tree branches stretches all the way across to the right and the base of the trunk extends a little way. This way the tree feels like it fills the composition, or claims the whole space for its own.
I used two brown Inktense pencils, a black and a dark green. I used the black to put down the outline of the tree, the big branches, and for shadow on the trunk. Then I filled this in loosely with the two browns, and scribbled some green in the branches for leaves. Notice how the scribbled blue lines done earlier for the sky add to the sense of texture in the branches.
Once I was content with the basic tree, I then painted the background...
