For Windows: Defender is the best choice IMHO.
And keep backups of your data.
If you want something foolproof, iPad or Chromebook are good choices.
To add to the parent I also use adblockers and turn off JavaScript
Frequent backups. Test them occasionally.
Redundant backups for precious data.
Just the naive way you'd restore a backup. Spot check restore files. Nothing crazy technical or unintuitive. Make sure the darn thing works every once in a while.
This perspective comes from talking to a tap backup operator at a major visual effects studio. Turns out someone somewhere was backing up to tape for years and it was all garbage, but they didn't find out until years and years and jobs and jobs later when they tried to do a restore.