Watch what happens when the sky goes in first When sketching a sky seen through winter's trees in watercolour, ignore the trees in order to be able to paint with gusto and with breadth. For the trunks and branches of those trees silhouetted against the sky will be much darker when you come to paint them over it, and consequently, it will look like a real, continuous, breezy sky beyond the trees. Simplicity, breadth, freshness and spontaneity of touch. These are the great virtues in watercolour.