Three things that you absolutely must do. Backup.
It doesn't matter how good your security setup is, or how careful you are about viruses. If something goes wrong, if you have a good backup in place, you can literally start again without any problem.
We would recommend a 3 pronged attack:
Backup or clone your main hard drive to a second hard drive installed in your computer. Use some backup software to daily sync the 2 disks, then if one drive gives up, you can immediately boot to the other one.
Backup to a removeable drive - use this for a full disk backup, so buy a removeable drive that's as big as your main hard drive. This is good for problems that might affect your main computer hard drive, be it disk failure or a virus attack
Backup all of your data files: music, photos, documents, banking data, videos, movies, to a cloud based back up solution. There's a number of them, which I'll review shortly. The advantage of this backup is that it's away from your physical computer, so if your computer is stolen, lost, destroyed, all of your important data will be safe.
It's not hard to do, but please don't wait until it's too late.
Protect the data that is essential and critical to you.