Most importantly, in the event of a failure, you need to know which copy of data you should go get depending on the event and location. In general, there are typically two types of failure events: You either need to return data to the most recent version available or you need to return data to a specific point in time. The location is dependent on if you are at your original location or at your DR site. You need to know how to execute a recovery in both of these scenarios and locations. The process should be documented well enough that a person with minimal IT expertise could follow the steps and recover data.
Finally, and this is critical, the plan needs to be practiced regularly. In my days of managing a backup support help desk, the number one tech support call was walking someone through a system or even file recovery because they had never done one or had not done one often enough that they remembered the steps. As the saying goes, practice makes perfect.
There is a lot more to putting together a tight DR plan than can be justified in a blog entry but hopefully gives you some ideas. There are also plenty of resources, such as Network Computing's Top Ten Best Practices in Backups and Restores (registration required) and Jon Toigo's DR Planning.org.