Here is the link to a website I've mentioned in the past. It's a fantastic resource for finding bloggers to review your book. For free!! http://www.stepbystepselfpublishing.net/reviewer-list.html.
The list, as you'll find, will tell you who reviews what. It makes it very easy for you. Click (or link) to the ones you feel will be the best fit for your book, then send them a query e-mail. Simply tell them what your book is about (adding links to where to find the book is helpful, too), and ask if they would be interested in reviewing it for you. It's that easy! Most will say yes, but they may need a large time allowance as they are busy people, too, and have many books to read on top of their daily lives. So be patient.
Obtaining reviews is HUGELY important for marketing your book(s). Readers like to know what other people are saying about the book they're contemplating buying. It doesn't always matter if the book is $.99 or $10.00 (or more!), most readers (but not all) tend to look for reviews first (I know I do). So, it's a good idea to provide them.
Aside from approaching bloggers who specifically offer reviews, ask fellow writers to review your book in exchange for reviewing theirs. If you are a member of Linkedin, join some writer's groups, they're rich with fellow authors looking for all the same help and advice you are. It's a wonderful resource.
Another piece of advice I'd offer in the search for reviews is to do a blog tour. I'm booked for my first blog tour the week of June 4th, and I'm excited! It's yet another opportunity to get your book out there as well as obtain people to read (and potentially review) you glorious piece of work.
If you aren't familiar with what a blog tour is, check out this website (http://www.goddessfish.com/tours.htm) for extensive information. They are running my tour for me, and they've been wonderful every step of the way.
Good luck, and happy hunting!
And as always, please feel free to leave a comment with any additional information or advice you'd like to add.