How to redo a 13 year old girl's room? I have a small room and I want to make it look great!?

Ok, so my room is like really small. Im talking like 10' by 8'. I have to fit a twin sized bed, bookshelf, desk, dresser, and a little nightstand thingy. What colors should I paint it? I was thinking like one wall light purple and the other 3 light blue. Do those colors sound good? Also, my bed is really high up and im tired of falling out of it every night. My parents can't afford to buy me a bigger bed, so I was thinking of just putting the mattress on the floor. Is that ok? Any suggestions on decorating or anything would be great! Thank You!