What is the best answer for "what system do you follow in filling documents?"

Make better classification of documents, and make sure that all the documents are filed in specific file/folder, on time, with proper tags.

 filling documents

There are templates can be modified by, within Adobe Reader Pro, the easiest design template on the program Microsoft is reportedly, is indispensable for both of them, both are important. 

as for the safe keeping of documents: 

Preferably Save a backup copy of the documents the end of each week, on an external hard disk and optical disc drive and raise the most important on the Internet at (Google Drive, Sky Drive).

For filing documents i am using drop box.