After staring at that last showcase pic for a while, I decided that I wanted to do a space pic like that.
But Painter doesn’t seem to have a Distort > Add Noise function anywhere. It has all kinds of really cool effects, but nothing that basic.
So I decided to see if I could do it with the airbrushes.
Starting with a black canvas, I got one of those airbrushes that just leaves a few dots at a time (I think it’s Tiny Spattery Brush or something like that), and painted in some very dark specks.

They’re in there, even if you can’t see them. It makes an important foundation for starfields, and they’ll show up later.
Picking brighter values of each, I added some red, yellow and blue stars:

Because the real night sky is full of all colors of stars, so a starfield should have something other than white. Or so say the various tutorials I’ve used.
I have all kinds of tutorials on how to make planets, but why go to all that trouble when deviantart is awash in stock planets?

They make nice moons. I just had to get them rotated so the light was coming from vaguely the same direction on both. I didn’t want the mysterious galaxy of twin suns. That’s just shoddy art planning. (Or Tatooine, but I digress.)
Now I dumped in a simple black-to-blue gradient. On top of that, I put a radial gradient of yellow-orange to black, then set the yellow-orange one to Hard Light with an opacity of about 45%.

Now for some nice swirly nebulae. I just scribbled around with a soft airbrush, then used the Smear tool on it. Then I added some lighter pinks and blues with the airbrush. Then I used more Smear tool.

It’s kind of like fingerpainting.
Yanking out that tiny spattery airbrush again, I put some stars on top of the nebulae on a new layer, then went back with the eraser and got rid of the ones that went outside the color clouds.

Here’s how it’s looking so far.

It’s time to do the glow effects and the really big bright stars, but I ran out of steam for tonight. That’s why it’s only part 1. 🙂