…cloud storage is the probably the best answer, but picking the right cloud storage is the tricky part. Spend a bit of time doing research so that you pick the right cloud storage for your needs. Do you need end-to-end encryption? How long have they been in business for, are they profitable, and are they likely to be in business decades from now? How easy is it for me to accidentally delete some (or all) of my files? How do they back up their files, if at all?
There isn’t any single one answer that works for everyone. But these are the solutions I use.
I have a master drive I store all of my files on, and a separate portable hard drive for backups. (I did experiment with RAID for a short while, but it got too expensive and impractical. And RAID (on its own) is not a backup)
I use Dropbox to deliver videos/logos/zip files to my clients and to back up finished video files.
I use Photoshelter to deliver images to my clients and it also is my primary backup for all my keeper JPEG images. (I currently have 359,554 images stored online: 2.272 TB)
I use Sync . com to store any files that need secure encryption.
I use Amazon Glacier to backup any mission critical RAW files and video files.
RAW video files get stored on an additional drive that gets swapped with another drive at a friends house regularly (and otherwise lives in a fireproof cabinet)
FYI I use 3-2-1 backup methodology. It wouldn’t hurt to have a look at this and adapting it to whatever it is you are doing now.