Here are some tips and tricks if your making space figs:

If your making a star bg, try to make it look natural and random. If the stars are clean around the sky, separated, and big, then you have an unrealistic star bg. It must be random, not entirely clean, barely separated, and the stars must be small to represent that they are far.

If your making a planet, use a reference first so you can learn from a reference and be able to make planets without one. If you wanna make a planet with rings, be very careful, try to keep it ellipsical and use a reference. Don’t add a back part to the rings, because the rings need to appear as if it goes around the planet.

I recommend to not make nebulae as a beginner, they are byfar the most complicated object to make.
Use a reference, choose a scheme of colors that you see in the picture, and put each color in the spot where you see those colors. Make sure the brightest part is white. After you are done with that, blur it, not too much not too little. The last part is complicated to explain.
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