Paint the available room a light, neutral color. You want the dark‐colored furniture to stand out against your walls.
Add accessories to your room in vivid colors to break up the dark‐colored. Don't clutter the room too much, but using a big brightly‐colored painting or a extra tall, glowing vase filled with plants may bring a whole lot of color into the room.
Edit the space. Even after you've carefully layered furniture into the room, stand again and make a decision whether there's anything the room can do without. If you want an item but it doesn't fit into the space, use it in another room or store it for later use.