Keeping your data Clean Current Unique and in the right place, is key to running a database.
Thinking through your site structure and thinking through your data structure, is key to getting things in the right place.
Keep your Data:-
Unsubscribes are often badly managed. If a custmer unsubscribes from your event, make sure you dont unsubscribe him from his magazine subscription, or he will be on the phone complaining.