Book Clubs

I'm in the process of trying to establish book clubs for my fourth grade students. My goal is to incorporate what I learned at a book club workshop and have students read on their level. I have a limited classroom library. I have been using my Scholastic points to aquire books, and one of our PTA grants was very helpful. I want to be successful, but I have only taught literature circles where the students have special roles. I was wondering if anyone enrolled in READ 525 has had experience teaching reading with book clubs. I would welcome any input or suggestions. I'm curious to find out what would make this experience successful.