Another nostalgic one, a nice idea for a picture. Just a small tip here, but when using sketch mode it can't think for you, so all lines are equally sharp or dense, and not all lines need to be there. For instance, if you had done a pencil sketch of this scene, the odds are you would have concentrated on your main subject - the pumps - and perhaps sketched the merest trace of the trees in the background. You can still do this in sketch mode, by making a selection of the trees, and blurring them, this can then lead to an illusion of depth in the picture. also wherever necessary you can set your eraser to a low opacity and thin out some lines, if you want to that is.
children paint because they don't know they can't - so what happens as we become adults? - Me
Life is very nice, but it has no shape. The object of art is actually to give it some, and to do it by every artifice possible - truer than the truth. - Jean Anouilh 1910-87