I received an email asking me to name common enterprise security mistakes and how to avoid them. The first three items revolve around knowing your environment. If you don’t know what houses your data, how that data is transported, and what data you are trying to protect, you have little chance of success. Security incidents will occur, so you should have policies, tools, techniques, and trained and exercised personnel ready to respond. You should also have a complete digital asset/intellectual property inventory.”]
Source: https://taosecurity.blogspot.com/2006/11/common-security-mistakes.html