There are only two types of people in the world: People with backup strategies and people who inevitably wish they'd had backup strategies. While you might be able to re-install your apps in the event of a disaster and perhaps re-download or re-rip your content, how will you re-create all your digital pictures, papers, documents, and everything else store locally?
Even today, in 2016, backup remains a huge issue for consumers, and one even businesses still aren't great at solving. If you're not thinking about backup, stop reading this right now and at least turn on iCloud backup.
That's the easy part, though. That's where many tips and how-tos usual end. Unfortunately, life isn't always easy.
Let's say you're already backing up your content locally and online or offsite. Will those backups really stand the test of time? I have boxes of floppy disks, SCSI hard drives, and other old media storage mechanisms that I have no longer have any way to access. I have files in old versions of MacWrite and PowerPoint that I can never retrieve. I have vinyl recordings and VRC cassettes that may never again be heard or seen. I have, in short, a huge pile of content that, even though it's "backed up", is still likely lost to me forever.
That's because backup is only one side of a strategy. Retrieval is the other, both now and into the future. You could have absolutely perfect copies—multiple copies even—of your old files, as written by Apple ][, Atari, or the original Mac, but also absolutely no way of getting to them again.
That's why I've begun to think ahead. I now keep my content in lowest common denominator formats. I use MP3 for music, for example, and JPG for photos. I'm profoundly slow to migrate to any new formats and, when I have any doubts, I keep a copy of the original format around too.
I also keep my stuff mine. I don't really trust any infrastructure that I don't own, and I'm not willing to take a chance on anything that's truly important to me. That's because even large vendors can shift directions, shutter services, get bought, change pricing, and so on. Online backup is great as an additional layer, but I also want a copy of my stuff on something that I own and can get to at any time.
By all means, back up well and often. Just make sure your backups stay alive and accessible so your content is really there when you need it.