Decorating a small apartment for Christmas can be a fun and challenging task. One of the most important things to keep in mind is space. You'll want to make sure you don't overcrowd the room or make it feel too cluttered. Instead, focus on creating a cozy and festive atmosphere with the items you have available. For example, you could hang a Christmas wreath on the front door or window, hang a string of lights along the ceiling or walls, place a small Christmas tree in the corner, and set up some small decorations around the room.