I work for a defense contractor and data loss is a huge issue. Actually it is they issue. One of the best things that you can do in general is to create specific procedures in the handling of the data that reduce the risk of data loss, and then educating the people in the company on how to follow those procedures and the importance of them(emphases on education, lots of it). These procedures should be enforced from the top down. Supervisors should administer them and ensure people are educated and periodically reminded that they should be following them. There are technical implementations that can be made to further reduce the chance of accidental data loss such as restricting the handling of certain data to restricted environments/networks that has limited access and is password protected. However those are very generic answers. Can you be more specific on the issue at hand and maybe we can provide better advice? Or are you just looking for a general answer?