When you create a Document Management System

Factors that should be considered before make a document library (SharePoint)
1) Types of document that we are going to store (upload)
2) Templates that we are going to use
3) Metadata that associated with the documents
4) Access control
5) Policy of the documents
6) Conversion of documents (if needed in future)
7) Ability to move documents away from the document library

Most of these features can be done by using the OOB features
1) Permission setting of the document libraries
2) Target audience of the document libraries
3) Select main type of the document that we are focusing on library

How to plan the document library
1) Define the roles
2) Estimate the usage of documents
3) Organize the document
4) Content types (metadata, features, properties)
5) Content control
6) Workflows
7) Policy management