I don't think I'm ever going to grow out of making paper chains.
I'm currently back to living with my parents (I'm only 19, it's not that bad.), and since my old room (much bigger) was turned into a mini gym, I'm back to the bedroom I had when I was 11, which is much smaller. It's really not a problem, but it does put a slight damper on decorating, because I can't handle a really busy space. However, paper chains are always a go, and I've got this globe I bought when I was living in Vegas. They're small details, but they've still given the room a festive vibe.