Well, there are a few tried and tested tips for adding festiveness to condos; the first one is the front door.
It is not surprising that condo owners will want to decorate their front door - it does not encroach on any of the interior space! You can have a free hand here - a decorated umbrella stand or large plant if it is allowed, a wreath, of course, and how about a pink bulb and some miniature balls for your front door lamp?
Once you enter, and if you have a mirror at your entrance, this is a good place to add some tasteful tinsel, balls or fir boughs. You may wish to group your Christmas cards here to keep the living room clutter-free, it depends how big your entrance hall is.
One way to add Christmas decorations to your home is to group them around a piece of furniture. Do you have a small console table that could be a Christmas feature? Of course, if you have a fireplace you have got it made! I would group almost all of the decorations around the fireplace and have a massive eruption of Christmas there and perhaps just place Christmas lights around the windows.
If you do not have a fireplace, maybe you have a balcony? Stand your tree outside the window on the balcony and light it up with external quality lights. Arrange the drapes to suit, and place large empty boxes that are gift wrapped under the tree - outside!
One of the tricks of decorating a small place is to keep the color scheme or the style of decorating uniform throughout. If the lights were all white or all yellow it would be less intrusive than multi-colored lights.
A bowl of Christmas colored candy on an end table can be effective and classy looking (and useful!) Make a centerpiece on the dining table or coffee table that is festive, fairly noticeable and in keeping with the Christmas color scheme.
If you think in terms of decorating from a vertical point of view, you will use less floor space. If you hang a wreath, let plenty of ribbons or tinsel or greenery hang down. If you have a center piece, make it a large statement. This way the impact will be there without all the clutter.