Oh gosh ahahaha I really just make sure the backgrounds/textures used for the bg match the character's colors or at the very least is somewhat similar XD Looking forward to seeing your your next GFX piece! <3
OH I don't create them all by myself. I download lots of textures/backgrounds/patterns and use those as my backgrounds! c: I just smash those already created bg/textures/patterns together to make a nicer background (unless the original textures already looked nice and matched the render) hahaha