I personally have a 2 way backup going.
1. I rsync over internet to a friend with a similar setup of mine, so we mirror eachothers data
2. I have a DROBO that mirrors my most valuable personal data
The problem with backup of data is the amount of storage, and most people have to prioritize, and I generally recommend you to make a simple listing of datatype, size and how easy you can replace them. Then from that list you prioritize and select backup solution. For the non-essential data I also mirror parts of it to Dropbox, Onedrive, Box and so on, so I have online backups as well. Using multiple accounts on those services, you can have a significant amount of data backed up into the cloud.