A common misconception is that only the main entrance to the home requires a mezuzah. To properly fulfill the mitzvah, every room in the house or office should have its own mezuzah...
Prior to affixing a mezuzah the following blessing should be recited: "Blessed are You, L-rd our G-d, King of the universe, who has sanctified us with His commandments and commanded us to affix a mezuzah"
The mezuzah is affixed on the right-hand side of the door as you enter. It is positioned on an angle, with the top of the mezuzah pointing toward the inside of the room . . .
Never use liquid cleaners because they may seep within the case and damage the parchment scroll. Mezuzah cases and mezuzah wrappings should be treated as genizah, which require interment after their use...
As a rule, a mezuzah should not be removed from a doorpost, leaving the room or house without a mezuzah, unless it will be put back or replaced with another mezuzah.
We are generally accustomed to not seeing the mezuzah itself, but its case. Most of us do not fully realize just how much skill and labor goes into the writing of the actual mezuzah.