Solutions that help support business rather than cripple it with overwhelming false positives are essential to success. Being able to look at historic data patterns will give IT the ability to prevent future data leaks. Once the patterns of use are identified it becomes easy to implement effective user education programs to start to change behavior and perceptions. That education coupled with systems that constantly monitor data as it moves around your network and provide immediate feedback to users and efficient tools to handle incidents quickly make the recipe for success.
The most effective way to prevent casual data mishandling is too raise awareness of safe data handling practices with your users rather than locking down your business by cutting off its essential access to the world which its customers live in.