Defender is "good enough" and lightweight
Install EMET -
Download Enhanced Mitigation Experience Toolkit 4.0 from Official Microsoft Download Center
Don't run as Administrator - use sudowin -
Sudo for Windows | Free System Administration software downloads at SourceForge.net
Run Malwarebytes Anti-Malware at least weekly.
Clean up monthly with CCleaner.
And have proven backups & system images offsite!
Mac