Share 'Writing book reviews'

I have only been doing book reviews for two weeks or so.  I'm wondering if there is a right or wrong way to write reviews.  Should I post what the book is about, my opinion on the book or both?  I am really enjoying writing the reviews since I am always reading.  I started my blog just to have somewhere to write them, but I always feel better when I get comments.  So far that's not going great.  …