3-2-1 like others say. Frequency depends on how much you tinker with your hosts. If your host type has a built in backup use that. Otherwise use a deduped and compressed method to a local USB drive and a cheap cloud storage for Configs and host images like hertzner storage box or something.

Remember you aren’t just backing up the data but also backing up the hours of effort it takes to rebuild and get it how you want. If frequently backing up just the service OS you can store heaps for $2 on offerings like OVH cold archive.

Remove yourself from the backup you’ll forget or it will be inconvenient the week it blows up, so automate it, check the automation monthly.