Usually I set out what colors I want as a palette, and then colorpick hex codes/modify to what I like. or i just find stuff and say "eh close enough" and put it all together.

there's a rule in art for confined color palettes that helps stuff look more cohesive. so if u had 2 colors, u would use one color and ite variants 75% of the time and then a different color that looks good with the first that u use 25% of the time, and you'd use this for stuff u want to pop out. example, blue for 75%, most of it is blue but then the text and stuff is gold and white (white being a variant of gold) and it would help that stuff stick out better!