guitar decorating?

[asscollection.livejournal.com]

I have an old FirstAct guitar. Yes, the lame Walmart brand--during my very short-lived guitar lessons, though, my teacher said it was surprisingly well-made! Anyway, it's been sitting in my closet for years now and I want to give it to my boyfriend's little sister, who is interested in learning to play. However, I'd like to decorate it. Some cool swirly designs on the body or something. Anyway, how should I go about it without it looking tacky? I was thinking paint would be the most convenient but what about decoupage?