Just a few suggestions. Initially, try first to attain a better balance of sky and terrain; i.e., 1/3 terrain; 2/3 sky. Next, play with the lighting so as to eliminate the flatness of the scene. Maybe your clouds are shadowing the area. If this is the case, try reseeding the clouds until you get better definition of the elements. You want to see some shadows and contrasts.
It would seem the ruins and the blossoming trees together would be the center of focus so as to draw the eyes to them - again, being placed using the 1/3, 2/3 rule for good balance. Regarding scale, those 10m cracks seem way too large. dandelO's cracks file come with 1m and 10m cracks. I would suggest you use the 1m cracks in place which may better suit your scale.
Finally, I note you always use the 800x600 ratio in your images. At the render tab, try to change the ratio to create a different size ratio - like maybe a panorama.
Take your time and experiment; this TG2 is quite comprehensive; and, diligence and patience will begin to pay off.
