Corporate policy tops the list of fundamental internal and external security practices.
Think about your security practices and goals, formulate a policy and put it in clear writing. Regularly conduct employee education and awareness training to keep employees updated on all aspects of company security and how they can be a part of it. Engage in periodic security testing and assessment to evaluate how your perimeter and internal security stack up against your policy. Make sure you use consultants who take a structured approach and lack a vested interest in the outcome of the project. Don't forget about the simple aspects of physical security.