Clouds, when your doing fluffly clouds use the airbrush, med to large, on low low opacity and flow, lightly begin to lay down a base, moving the brush at all times, making sure the background comes through. Consider the light source and make the highlights brighter on top with a reflective light on the bottom. Use the tool trick and turn the brush into an angle brush to bring out the shapes. These are a beggining but it's too inky (unless you were going for that) And the color of the sun/sky should be added to the clouds as you've done. And shading, it'll make your clouds stand out. Just build and build, don't be afraid to use the erasure on the lowest setting to take some of it away (you can get some nice wispiness that way) I hope what I wrote made sense.

hope you do more work on this - the colours are really interesting.. Im thinking a Mars Sky....

Sweetcell, please tell me how to use the airbrush on Lascaux sketch and how to do the tool trick again.

No problem Cameo.

I'm liking that too...