Keep 3 total copies of your files, on 2 different types of media (e.g. internal drive + external drive), with 1 copy stored off-site or in the cloud. It protects against both hardware failure and local disasters.
Consistent naming makes files sortable chronologically and instantly recognizable at a glance, which is much faster than relying on search across thousands of files.
Most creators are safe archiving raw footage after 90 days once the final edit is published and backed up, unless you regularly repurpose old raw clips.