Mirrors - enlarge and enliven a space
Feng Shui mirrors are used to attract, move or change the flow of energy. The placement of a Feng Shui mirror is used as decoration or to attract energies to the home. Using a mirror in Feng Shui is one of the most typical of energy adjustment tools. Mirrors enlarge a space, deflect something, flatten a wall, or make a wall disappear.

You will consider mirrors reflect what they see back at you and that includes energy. Different kinds of mirrors are common in Feng Shui. The most typical types of mirrors are round and octagonal styles in Feng Shui.

Find the best quality mirror for most adjustments. If a mirror is of poor quality, the mirror image will be distorted. Mirrors should be whole and complete, not the small mirror tiles often found. The small mirror tiles cut the image into pieces.
There are certain places where a mirror is not desirable. Mirrors placed at the end of a long hallway only reflect a longer hallway. Mirrors reflect back what is in front of them, so if a room has a lot of clutter, the mirror will reflect even more stuff. Mirrors in bedrooms could be startling when the person awakes.

Mirror helps enlarge the space.
Mirrors are good to place in small rooms as the space will feel larger. Objects can seemingly “pass through” a mirror and it is possible to open up a space or make a wall disappear. Mirrors bring the water element into the space so they are ideal in the career area of a home. Mirrors are also good by a front door as they welcome wealth into a home. Mirrors are ideal when trying to harmonize the energies of the home. If there is a missing piece of the bagua, a mirror can “move” a wall to fill in the gap.
Try working with mirrors and see how they reflect the world back to you.
Source: Feng-shui-products-decorating-tips