Feng shui mirrors are a special object, which should be used with caution.
Let's take a look at the properties of mirrors: they reflect, attract, create the illusion of an extended space, complement the space visually, and redistribute the Qi energy flow.
A mirror can be an excellent corrector, such as in a bathroom. The Qi energy is attracted to water, and moves with water. If you keep your bathroom door open, then good luck may be going down the drains. In this case, the best corrector is a large mirror (the size of the door) hung on the outside and inside of the door. On the outside, it will reflect the Chi and keep it from entering the bathroom and flowing out of your house. On the inside, it will not allow the negative energy to penetrate into the home from the bathroom.
If your bathroom door is opposite the entrance door, it's best not to use a large mirror on the outside of the bathroom door - it will reflect the incoming Qi back to the street. Instead, hang a small round mirror on the inside of the bathroom door, and hang a wind chime on the outside. The chime will pick up the incoming Qi energy and scatter it through your home.
It is best not to use mirror tiles, as they "cut" the reflection. Good Feng shui mirrors should reflect a person completely, with a little space above the person's head - it's the personal growth potential.
Mirrors can help to direct the Qi energy in the desired direction. For example, if your kitchen is opposite the entrance door, you and your guests may be tempted to go to the kitchen and eat. This is not surprising, since the incoming Qi goes straight to the kitchen. If you hang a large mirror to reflect other rooms, the Qi will be redirected towards the rooms and you'll eat less.
Feng shui mirrors in the bedroom are fine, as long as they don't reflect a sleeping couple. If they do, the relationship may suffer from third party interference.
Mirrors in the kitchen are used in two ways. First, to reflect the dining table - this will double the prosperity of the family. Second, for the cook to see who enters the kitchen - this will make him/her feel safer.
Mirrors in the living room can help to enhance it. For instance, if you have a stunning landscape outside the window - hang a mirror on the opposite wall, and the beauty of the landscape will double.
The round Bagua Mirrors with rings of trigrams are very strong protectors, which attract negative objects and restrain them by the forces of nature. Bagua Mirrors are very potent and need to be used with caution. Instead, you can use friendly protective animals, such as turtles and unicorns (Chi Lin), which protect against negative spirits and people.
Let's remember the rules for placing the feng shui mirrors: they should reflect a person in his/her entirety; a mirror opposite the bed can harm a relationship; let the mirrors reflect only nice things.