For all of my drawings that had the sky in them, I’ve always used a 2d brush, but it’s never really worked. Now Im working on a project where the sky is going to be really important, and I want it to actually look good. I’m specifically asking DeeVee this, because all of his wonderful landscapes, but anyone else who wants to answer can.
David
You could check the Quicklinks above. There are a few ZScripts that demonstrate different techniques for making clouds.
here’s some cloud material.
you can apply it to a 3D plane and to get different cloud effects you can change the noise radius one point at a time. The noise radius is in the Materials 
Modifiers at the moment it is 250 but if you change it to 251 for example you will get a completely different sky.
You will need to set the colour to white
here is the material with 4 different noise radius settings. The effect is similar to the clouds filter in photoshop but a bit more predictable. that is the same radius setting will always give you the same cloud. Although changing the position of the plane will also change the clouds.
I use that cloudy looking brush, and the drag stroke. Using a light touch I mix the colors etc. Course I’m the newbie, lot better info and scripts on quicklinks.
Hanuman,
Nice sky texture. 
I use a base color of blue around 198,188,255. Then I use Brush 04 with an RGB and Z-intensity of 8. I choose a pink color somewhere around 255,174,229 and I lightly dab color over the canvas. I don’t drag at all, just a mouse click until I have enough pink across the area I want clouds. Then I do the same thing only with not as much coverage with a yellow somewhere around 255,240, 207. You can see things starting to shape up, getting depth etc. Then I use white and set the brush size a little smaller and dab on white for highlight. Then I take the highlighter brush and lightly dab highlight.
Creates a colorful sky and not necessarily realistic. If I’m looking for a stormy sky then I don’t use the highlighter brush yet, I start with a brighter pink and yellow and the next step after the white is the blur brush using alpha dots brush and swipe on the canvas until I get what I want it to look like. Then I use the highlighter brush if necessary.
If I’m really looking for some depth then I leave ZAdd on and use the default brush to apply the colors, dabbing and a very light touch, and the blur brush with the dots alpha very carefully to shape them.
But, my skies aren’t anything like you see with DeeVee and others. I’m a beginner also. Think I’ll give Hanuman’s texture a try. 
Vikki,
It’s not a sky texture. It’s a sky material. There is no texture applied at all. However it does need a blue colour set in the colour palette. This is why I posted the material because most skies are painted whereas this contains no painting work at all and is continuously variable by altering the radius values.
I’m not sure if you realised this and just wrote “texture” by accident.
Oops, yep I meant material. 
I’ve downloaded it several times now and I can’t open it. I get a “ZBrush has encountered an error and can’t load…”
I do see a cloud material in my materials folder that I missed before so I’ll play with that one for now.
I don’t know why this happens sometimes. It works when I download it but this should fix it if the zmt won’t download. I’ve zipped the material.
You can use radius setting from 30 to Maximum. 30 gives you wispy small clouds and 500 gives you large fluffy clouds.
Also it is worth noting that you could make a cloud this way then mrgbz grab it and convert the texture to an alpha which you could then use with a drag dot brush.
Hi Hanuman,
Thanks for fixing it. I’ve got it now and it works perfectly. I do have another cloud material. Can’t remember if I picked it up from somewhere before or not, perhaps it’s yours that I grabbed from another thread somewhere. At any rate I’ve got this one now too. Thanks! I’ll play with it for a bit now. So much easier than painting it on!