Mezuzahs

I must tell you here that the most imporant item in a Jewish home is the mezuzah. If you are going to make one investment and you have 100 dollars and you dont have one, buy one and affix it to your front doorpost.  I must admit that until I had returned to live with my mother and father at the age of 27, I never had a mezuzah on my own that was kosher. (well in my last apartment I had a mezuzah that my grandmother gave me.  It had sentimental value and I affixed it without a prayer to my door.  The mezuzah klaf inside was almost black in places due to exposure and time.  This has no spirutal value. It just serves to make you "look" jewish. Which is still a mitzvah, but one that really has little spirutal health value).   I began affixing mezuzahs religiosly to my home about 4-5 years ago.  They are easy to obtain.  Just go shopping online. A nice one will cost you abotu 30 dollars for a nice case and 40 for a handwritten kosher klaf. It MUST be kosher.  Period.  If it is not kosher, its like you were robbed.  Dont take a chance. 
I have since placed mezuahs on the garage entry and 3 first level doors to the house. (I am yet to get one for the basement entry from the backyard.).   I have one on the staircase going upstairs.  And 4 on the bedroom doors.  Surprisingly I am extremely impressed that my father and mother agreed to even buy one for their own bedroom as I had thought they felt that my "obsession" with mezuzahs was a fruitless and annoying habit.  I am ultimately proud of their trust.
I happened to be in a room a few shabbas's ago and found myself in the mode of thought asking "is this room how it really needs to be".  I had no idea, but somthing felt as if it was a miss or that there was somthing I needed to add to the room to make it work for me in a spirutal or psychological sense. Its a beautiful room with a beautiful oil painting.  No televisions or electronics.  A nice book case for memorabilia, books and family photos. I always felt that this is where our family was most blessed in our home.  I labored over thinking perhaps I needed a specific book to add to the room.   Maybe a photograph was missing. I didnt know. I knew however that this line of thought was important.  I finally realized that it was a mezuzah that was needed.  In truth this is my room of rest for shabbas hours where I may lay on a couch or sit in a sitting chair, read or just reflect on my lifetime.  I am glad to report that soon a new mezuzah will be affixed to the doorpost.  The same gold metal one that is on our staircase. It will look really nice.  I do have a few other rooms without a mezuzah right now.  Perhaps in time that will be added.  They are indeed expensive so I can not complete this project overnight.
In affixing one to the garage door outside, I wondered to myself if I was indeed doing a mitzvah or if I was making over kill. It clearly is a needed item.  Any entry way both in and out of the home needs a mezuzah. It offers spirutal protection to the house, keeps you mindful of Torah, and brings our Creators presence into your home. Its kosher. I theorize that it helps you keep kosher thinking and it blesses your day.  I am in the habit of kissing my fingers after I touch almost evey one I pass in our home. It is not a silly practice. You form a connection with the everliving Creator by doing so.  The mezuzah is a living item.  On outdoor mezuzahs the practice is to check them at least every 7 years. Every 3 years I do believe many do.  It must be kosher or it is worthless and just an emblem.  They really do have power. 
For your edification, here is the prayer over the ritual of affixing a mezuzah. You do not need your rabbi to put one up for you.  Just put it up and say the following bracha:  Baruch Ata Adonai Elohainu Melech HaOlam, asher kidishanu b'mitz'votav v'tzivanu lik'bo'a mezuzah.  Simple. 
I noticed that one of my reform rabbi friends had mezuzahs on each bedroom door in his home many years ago.  That memory stuck with me. 
If you are in any place for over a month, it is important to affix one at the enterance.