Cloud studies in watercolor and gouache:

For this gouache study I painted in the sky color first and then layered white and grey tones on top blending out a few edges to soften them.

 

For my watercolor study I painted the sky color first with a pretty wet wash and then blotted out the cloud shapes with tissue.  I went back into it with the grey tones and softened edges with a wet brush and blotted with tissue to get some variation.  I finished it with white gouache highlights.