Well painted clouds come with practice. Most established landscape artists have a certain unique style about there clouds. You can practice clouds on scraps of canvas and become familiar with the brush strokes and the colors used to give the clouds the required shape. Paint an undercoat in the color of your sky, remember to blend your sky from dark at the top to very pale at the bottom. (white even) Then you can paint your clouds over a dry sky or paint wet-on-wet. Keep the clouds big, at the top of the sky and smaller, in the distance. A grey can be mixed using Cobalt Blue, a little Crimson and a very little Raw Sienna. A golden glow is produced by adding the littlest tint of Burnt Sienna to the white at the top of the clouds. You must keep your grey tones soft, there is very little tonal diffrence between dark and light clouds.
Complete training DVDs are available at www.lenhend.com