How do I select themes for my apartment?

So of course living in an apartment I have to deal with small and white walls. (hopefully I can paint them). How can I choose a theme for everything? (kitchen, living room/dining room, bedroom) my bathroom is already done (brown, tan, black, green) it's a bit earthy...can someone give me good ideas or websites to check out some pictures or something. I'm not to creative when it comes to decorating, but I want to learn.