Here are Marie's guidelines on Christmas tree placement from the Diamond Feng Shui Series 1 Winter Newsletter:
Place Your Tree According to the Five Elements. Because of its shape, color, and element, the best area to place your Christmas tree is in the South of your living room or family room. The wood element and green color support the fire of the South, and the tree’s cone shape is an excellent South activation.
The wood element is also favorable for an East placement.
A third option is to put the tree in the Southeast, but only if it’s a smaller-size tree, because the Southeast is represented by small wood. Large trees, five feet or taller, should go in the South or East; trees less than five feet in the Southeast.
If you cannot place the tree in any of these areas then try West or Northwest, because the wood element will not weaken or destroy the metal energy of those areas. However, the fire shape of the tree destroys the metal element, so make sure you add a lot of white, gold, or silver ornaments or garland to a tree in these areas.
You will weaken the power of the North if you place the tree there. If it must be in the North, then use blue ornaments or garland to support the water element there.
In the Northeast, Southwest, or Center the wood element of 6 7 the tree will destroy the earth element of these areas, but the fire shape enhances it. To make it stronger, add red, purple, yellow, or rose ornaments or garland to the tree.
All the best!