1. Plants. Plants are a wonderful solution to bring life, literally, for you to fill the space and the people "What on earth do I put in this room" area.
2. Furniture does not fit. Please, I beg those who are looking for new furniture set, do not buy a complete set. This is not creative. If you already have furniture that is not a good fit for you! (Or, sorry it was you who took the couch from the curb and that's why you do not match the furniture.)
3. Art. How awesome is this artwork. Perfect contrasting colors and told by the art, you may be able to find some kids in Craigslists paint something similar to a bribe from the McDonald's gift cards.