Take a look at CIS benchmarks and DoD STIGs. Many companies are starting to harden their infrastructure using these standards, depending on the requirements of the environment. Once you get the hang of it, then automate deployment. DO NOT blow in ALL of the rules at once. You WILL break shit. Every environment has security exceptions. If you’re running Active Directory, run Ping Castle and remediate any issues. Audit often, make sure everything is being monitored.