Adding my re"view"-why has it taken so long?

I am one of those people that before I buy anything I always like to check the reviews-whether it be a hotel, electronic device, kids toy I always check out multiple sites to see other peoples "views" of the product.  I use websites like amazon.com, travelocity.com, and even the company websites to see what other people are saying about the product/place to see if it is worth the price/dependable/reliable/built to last.  The funny thing is I have never taken the time to complete the reviews myself for the products I have bought.  What is holding me back-if I put so much stake in what others say (they took the time to review the items) why have I not taken the time to do the same for others?  I can blame it on lack of time but to be honest I think it was just not really a priority for me.  This new blog I am writing is helping me see the things I do and don't do in a new light.  In a society where sharing info and resources is common place I should not keep taking without giving back.  With that being said I wrote my first review for trip advisor.com today on the things we did and where we stayed at Mammoth Cave this past weekend.  It felt good to let others know how the campground and cave tours were and let them make their own educated decisions if that is where they want to stay and if the tours we went on would be good for their trip.
Do you read reviews before you buy?   Do you write reviews yourself?  If not what is holding you back?