I started with creating lasso selections for each layer of trees and branches. I also pre-created tower selection in the BG. After that was ready painting time was around an hour. I locked layers transparency for accurate edges painting. Custom brush was used for the leaves. Painting time of the final ( attached ) version was 2.5h. The last stage on the progress gif image was prepared at 1h mark.
My inspiration was work of impressionists, also - for a long time I haven't gone so mad with color :)