As always, I love Little Twin Stars and am obsessed with their pastel colors, gradient backgrounds, and celestial stars and moon artwork. I was inspired recently to create imagery around this. I made the moon the main focus point for this and sprinkled stars and sparkle effects throughout the background.
In general, to keep images from looking too 2D or falling flat, I like to add in other effects to bring in some type of texture to the backgrounds, especially after adding in a gradient. For this piece, after adding in the pink to blue gradient in the background (with mixes of pastels and brights), I also used a couple special effects to include other types of patterns to it.