Mirrors are pathways into other dimensions!! Well they could be, as they are one of the most powerful energy multipliers I have seen in the Feng Shui world. Their element is water. and they double anything they reflect. So placing a mirror is critical. Here are the rules that you should follow
1: Make sure the mirror reflects something good. Like a flower vase or a window with a view. Something you want to increase in your life. Anything that is symbolic in its adundance. If you are not that lucky make sure the mirror does not reflect clutter.
2: Do not place it in a region which is governed by fire element unless you are trying to fix the missing corners problem. Mirror belongs to the water element. It can be used to balance fire only if it does not reflect a fire element.
Fire Element is great but in small doses. Fire governs passions and it does not take it much time to transcend into violence and anger. Look at this Red Room, the mirror cannot dose the fire in this.
3: Mirrors Should not be opposite doors. It will send the good energy back. They can reflect toilet/powder room doors as it sends the bad energy back.
4: Mirror should not reflect the bed. You will have someone else enter the relationship. It does not mean that your spouse is going to cheat. It could be the interference of an in-law or a friend in the relationship. This is the most common mistake I have seen.
5: Don’t break the mirror into pieces no matter what your interior designer tells you.
This one looks fabulous but its not good Feng Shui. The small mirror border splits the image into multiples like a broken mirror. BAD FENG SHUI. USE ONLY SINGLE MIRRORS !!!!