First: One thing I learned many years ago (more than 20) is that you should do backups so you are covered WHEN your hard drive fails. Always assume that at some point, your hard drive will fail. I had one fail on a new computer that was less than a month old.
Second: Make sure that your backup system is automated. DO NOT depend on remembering to do backups manually yourself because almost invariably, when you need the backup the most, you will find that you haven't done one for quite a long time. I ran into that situation one time and realized that my last backup was over 3 months old.
Personally, I have two backup systems in use on my current system. One is local and uses a Seagate Backup Plus Slim Drive (available in 1 and 2 Terabytes, they have other, larger drives available). It uses a USB connection to my system and, once set up and activated, needs no further action on my part to keep backups up to date. My other backup uses Carbonite (see
http://www.carbonite.com/) which does backups to the cloud (effectively giving me offsite backup - something many consider very important). Again, once set up and activated, it needs no further action on my part. Both systems keep things very up to date (presently, my Carbonite backup says it did its last update 17 minutes ago).
I know there are other systems available so do a little checking. Look for systems that are automated, and preferable include one that stores the backup in the cloud so even a major disaster will not wipe out all of your hard work.