"A successful watercolour (and any painting for that matter) has a balance of soft and hard edges.  This is the same for skies. Watercolour is an excellent medium to provide the subtle blending of warm and cool colours and to create the soft edges of the clouds.  Although the painter has to be confident about the process.  There cannot be changes, or scrubbing or second layers if you want a fresh  and lively rendition.  This takes practice -  many miles of paper and paint.  If it doesn't work the first time grab another stretched sheet of rag paper and give it another try."

"As with foliage where you focus on the colours other than the greens, in skies you don't have worry about the blue - the blue takes care of itself. Look for the warms and other colours in those clouds."