As a start, follow the 3-2-1 rule:

• At least 3 copies of the data.

• On at least 2 different devices / media.

• At least 1 offsite backup.

I would add one more thing: invest in a process for verifying that your backups are working. Like a test system that is occasionally restored to from backups.

Let's say what you care about most is photos. You will want to store them locally on a computer somewhere (one copy) and offsite somewhere (second copy). So all you need to do is figure out one more local or offsite location for your third copy. Offsite is probably best but is more expensive. I would encrypt the data and then store on the cloud for my main offsite backup. This way your data is private so it doesn't matter that it is stored in someone else's server.

I am personally a fan of Borg backup because you can do incremental backups with a retention policy (like Macs' Time Machine), the archive is deduped, and the archive can be encrypted.

Consider this option:

1. Your data raw on a server/computer in your home.

2. An encrypted, deduped archive on that sane computer.

3. That archive regularly copied to a second device (ideally another medium) and synchronized to a cloud file storage system.

4. A backup restoration test process that takes the backups and shows that they restores important files, the right number, size, etc.

If disaster strikes and all your local copies are toast, this strategy ensures you don't lose important data. Regular restore testing ensures the remote copy is valid. If you have two cloyd copies, you are protected against one of the providers screwing up and removing data without you knowing and fixing it.