@picklechip yoo it looks like we use similar brushes! raddd
This is just how I do thing but when I do space drawings like this one
I take a lot of time to blend out the colors and make sure that the colors are really transparent, so it looks like you're looking through gases in space instead of having the colors block your view. The more things are blended, the better they look, and you can go back over it a few times and add more color to areas you want to be more opaque instead of doing it all at once. For me it takes like two or three hours to get the sky looking right most of the time, and most of that is blending and reapplying to give it more depth.
Also for stars, I think the best thing you can do is go in with a pen or maker tool and put in some main stars in pure white, then go back on a very slightly off-white or gray color and add smaller, dimmer stars. This way they have a bit of character to them, and they look more natural.
Playing with layer settings is also really fun, I think color burn sometimes produces interesting results with this kind of style.