NIST, the US National Institute of Standards and Technology, have released a draft version of their Special Publication 800-123 “Guide to General Server Security” for comments. The document provides guidance to those wishing to ensure their servers are secure.
NIST provide an invaluable range of guidance documents to help you secure your network infrastructure and information systems. I would recommend you have a look at their site and review their guidelines. The Center for Internet Security is also a great resource.
It is a draft standard so feel free to submit your comments and feedback to NIST if you feel there are areas that need improvement.