1. if you're running a hosting a website, you can add modsecurity/php ids to it to prevent webbased hacking.
2. limit the services that you're supposed to run(if some services are only used once in a while, then turn it off and turn it on based on demand)
3. if certain services are only to be accessed by you, then limit it to a predefined set of ip for better security(like ssh)
However, "Never use old/outdated script/software/OS" -- provided that it doesn't breaks anything, so, always do a backup before upgrading