The summary.
THE FOUNDATION
Updates, applied automatically. Every day between a fix being available and applied is exposure.
Check monthly that updates are actually applying. Devices stop updating without anyone noticing.
THE TWO SETTINGS THAT MATTER MOST
A screen lock with a short timeout, and drive encryption.
Together they mean a lost or stolen device is an inconvenience rather than a breach.
WORK UNDER A STANDARD ACCOUNT
Not an administrator one. It contains the damage when something runs.
THE BROWSER IS WHERE MOST RISK ARRIVES
Limit extensions and review what they can access. An extension can read everything you do, including passwords.
WHERE TO GET SOFTWARE
The developer's own site or the official store. Never search advertisements, aggregators, or pirated copies.
FOR PHONES
Your phone holds your email and your authentication codes. Treat it as a critical device.
A phone no longer receiving updates should not hold business accounts.
BEFORE DISPOSING OF ANYTHING
Sign out, remove it from your accounts, then wipe it. Deleting files does not remove them.