Mirrors are good for reflecting the light of the day and happy energy. However, they should never be placed on walls that are directly adjacent to one another. In feng shui, mirrors should be positioned in a way to reflect the best energy. For instance, it would be a bad idea to place a big mirror on the wall directly opposite the laundry room, which is considered a “drop zone” because it doubles up as clutter. Check out Feng Shui mirror placement for luck.
The best place to place a large mirror is the dining room, which is the most ideal place for them. If placed in a crowded area, the mirror will create the impression of wealth and increase the room's capacity to store wealth. But don't put a large mirror on the wall opposite the door or on the end of a long hallway. Or, don't place a mirror opposite a stove, because it will interfere with the energy flow in that space and increase accidents.
Mirrors should never face a doorway, as the reflection will draw negative energy into the room. In feng shui, a mirror should be placed at least four feet above the floor, so it can reflect the view outside. It should also be positioned at the top of the stairs, because this placement will cut off the head and feet of the person walking up the stairs.