To start, decide what absolutely does NOT need to be addressed! One of our subscribers asked us to review the article posted on Jan 13th by Janna Bastow titled How to Clean Up a Big Messy Product Backlog. In this article she discusses the steps needed to clean up and maintain your backlog including: 

1. Gather ALL of the information
2. Get the information organized
3. Get the work all in one repository 
4. Make the Backlog actionable 
5. Create a plan