Hardening Tips for Mac OS X 10.6 ‘Snow Leopard’ have been offered by the National Security Agency (NSA). It is a tri-fold security booklet for the agency’s Information Assurance Mission.
Honestly, some of the NSA’s suggestions are brilliant such as FileVault for laptops, non-admin accounts, disabling (at least through software) unnecessary services or hardware.
Although the aim of these tips is Snow Leopard, most of these tips apply to old Leopard as well as Lion. Some general advices even apply to just about any system. However, while the advices are simple and practical, a security-conscious workflow is a prerequisite.
For instance, creating a user account particularly for surfing and reading e-mail is suggested by the guide. Numerous single-user machines read mail and surf in the primary account, which is often the Admin Account for the machine.