Alternate Sign-on Have an alternate sign-on with a different password for your laptop / pc.
In this way if your main sign-on is corrupted you have this to fall back on.
Attachments Be wary of opening attachments, particularly if you do not know the sender.
Attachments can be something like a word document, a spreadsheet, a picture.
Backups Take a regular back-up onto an off-line device or onto a cloud backup provider.
If you find this to time-consuming, do it less regularly but back up your most used files onto one or more memory sticks.
Keep more than one backup, for example, last week, two weeks ago and three weeks ago.