Help with bedroom painting ideas !?

I change the color of bedroom probably every six months. It's ridiculous! I wanna stick with my room color for longer than that. So I decided I was gonna re paint it sometime soon. My room has been yellow, pink, blue, purple and last year I started to do two colors at once, so I had it orange and green, then I figured it was too kiddish for me, I'm going on 16 by the way hahha. Right now it's a muted plum on one wall, and the rest are a really light pink then on the muted plum I splatter painted it. But again I feel thats too kiddish. So this time I was thinking of doing like a sandy color and maybe turuqoise and a sandy color or like a caribbean blue with a sandy color but I can't just paint the walls, I need a design or some sort of something in it so it's not just a plain wall. Ideas? D: I don't have to do the colors I suggested they could be something else. Heeeellppppppp,