Managing what items are associated with which discount rule can be difficult as you get more rules and more items associated with each rule. But one of the ways that have been successful for customers is to use Class filters.
When creating a discount rule you are required to set a filter on your inventory that tells RetailEdge which item the discount rule is to be applied to. If you keep this filter simple and class (or Vendor based), it makes it much easier to manage which items are on sale.
For instance, say you are running a promotion on Wine. You might want to create a Class called Wine promotion. Then create a discount rule for the promotion (say 20% off a case).
To manage what items are in a particular promotion all you would need to do is open your inventory and set a filter on the Class Wine Promotion and you would be able to easily add or remove items from the Promotion and the particular discount rule associated with it.