Always keep a backup of your data in a SEPARATE LOCATION from your main copy. This can literally be in the form of a high-capacity flash-drive kept buried in your backyard, an external HDD kept at your grandma's house- whatever, wherever. The more copies, the better. Maintaining multiple copies can be troublesome, so just keep what you deem absolutely essential in a few places, and keep everything on your main device.

Here are some cheap, easily-stowable options for mass-data storage, but please, do your own checking:
https://www.amazon.com/dp/B01LQQH86A/
https://www.amazon.com/PNY-Turbo-256GB-Flash-Drive/dp/B00JN1TOHM/

If you want to use a Cloud service, you can try Google Drive or OneDrive, though I would recommend against these mega-corporations. Mega (www.mega.nz) offers a free 50GB storage space to each account (10x what OneDrive gives), and the plans are pretty cheap. If you want your data stored, and public, you can use The Internet Archive (www.archive.org); you can upload data here for all to see, and your storage space is essentially limitless, as their servers are undoubtedly massive.

All this said, it is best-practice to, at least once a year (and most will agree that this is pushing it) to take your backup devices, cut (Ctrl+x) all data from it, then paste the data back into the device (there are applications that do this as well). Over time, data (especially in solid-state devices like SSDs, flash-drives, etc.) can literally migrate or decay, resulting in data loss.
Here are some articles on this subject:
https://www.prosofteng.com/blog/long-term-data-storage/
https://www.digitaltrends.com/computing/keeping-data-safe-eternity/