Best Practices for Adding New Data to Saves

[tnsi]

I'm currently beginning work on a significant collection of scripts, which adds significant functionality to an RM game- but also handles a large amount of new data that doesn't exist within the default scriptset of RPG Maker. Is there a best practice for adding new data- while retaining compatibility?

Basically, what I'm seeking to do is define a new set of data within the save file that handles another set of variables, and I don't want to conflict with existing scripts or access variables accessible in the RM GUI.