|End of Day Calm, pastel, 9 x 12|
As I've studied the paintings of artists who paint this subject matter quite well, I've noticed that those elusive "lost and found" edges are key. If you sharply define every line and edge, this is what will give your painting that unwanted stiff look. It's just more information than the painting needs.
I think that the method you use to begin the painting can help you loosen things up while still keeping the line work accurate. I began my demo, End of Day Calm, by drawing in only the largest shapes and then blocking in large areas of values with two dark purple pastels (one darker than the other), which I wet down with an alcohol wash, creating a monochromatic underpainting. In the underpainting stage, I looked for opportunities to connect large shapes of similar values, to create even larger shapes. For example, I initially blocked in the background trees, blue buildings and roof of the center blue building as one connected dark value shape. This simplifies the composition from the start. I then pulled out lighter and darker sections, keeping all edges soft at this point. Then, as I started to "construct" the buildings on top of these loosely defined sections, I could pick and choose which edges I wanted to more sharply define.
One way to "lose" or soften an edge of a structure is to place it against a similar value (such as the roof of the barn against the sky...notice it contrasts slightly more on the right, but becomes more lost toward the left). Another way is to lighten the value or intensity of a highlighted edge only in certain places...not along the entire length (such as the whitish trim on each side of the barn and on the highlighted trim along the roof line of the blue buildings). I also kept lots of soft edges in the foreground grass and background trees. This way, when I added the small, crisp details of the fencing and other misc. farmyard equipment, it would contrast nicely with these soft edges.
We'll do at least two more weeks of buildings and structures in my classes, so stay tuned for more on this subject!