Attached Link: 5. Spectral clouds II

In that case, may I add the suggestion that you start with a basic tutorial from geeatplay.com in the 'vue 7 overview' section (see link above), tutorial 5. Amy is showing the effects of changing the sharpness and feathering sliders has on the cloud layer. Repeat her experiments render and save the images. Then, do the same with the other sliders - change the value (by a lot so the effects are clear) and save the image. Last stage - change parameters in the cloud material editor(double click the little picture) and change the parametrs there. At the end you will know all the tools that are available to you and  have a library of images which you can use to design the effects you want.

I know it sounds tedious and not at all glamorous, but it is almost garanteed to bring you to where you want to be, whereas at the moment its painfull to see how you dart from one aspect to another without sorting anything out.

Best of luck

"I paint that which comes from the imagination or from dreams, or from an unconscious drive. I photograph the things that I do not wish to paint, the things which already have an existence."
Man Ray, modernist painter
http://artpearl.redbubble.com/