Mirrors are used to add light to a room, or to give a room a more open feel. They are also practical and used as such, placed in a bathroom over a sink or on the wall above a vanity. The location of a mirror is the most important thing to consider when hanging a mirror. First, if the mirror is heavy, you must hang it on a stud or at the very least, in a wall where you can install anchors. Drywall would probably not be a good choice, nor would a brick or concrete wall. Second, Make sure that you don't hang a mirror too high on the wall, unless it is going to reflect a window. Hanging a mirror opposite a window is a great way to increase the light in a room. Hanging a mirror too high, however, means that the occupants of the room can't see what is reflected in it and the mirror is reduced to a gaping hole rather than a decorative accessory.
It is important to consider the impact of the mirror on the rest of the room. There are some traditional places to hang a mirror, such as over a fireplace or buffet in a dining room. One thing that most people don't realize, however, is that the mirror needs to be the proper scale for the location. A mirror that is too small will look ridiculous hanging over an elaborately carved fireplace mantel. A mirror with a simple frame will look just as out of place. The more elaborate the fireplace or mantel, the more elaborate the mirror should be. Alternately, a sleek, modern fireplace needs a sleek, modern mirror hanging above it and not a monstrosity in a gilt-gold frame.
Outside of the Box
Hanging one mirror over the sofa, fireplace or a buffet may be traditional, but it can also be boring. Instead, try hanging several, smaller mirrors. For a modern look, hang several small perfectly square mirrors in a straight horizontal light above a sofa. For a more whimsical look, try hanging round mirrors in a random pattern so that it looks as if bubbles are floating down your wall. If you are placing a mirror over a fireplace mantel, consider leaning several tall, rectangular mirrors of various sizes on the mantel itself instead.