There are many ways to keep your computer files and data safe:
1st- How much do you want to spend?
2nd- How big are ALL the files in question?
3rd- What are you protecting them from?
1- Cheapest way would be on flash drives, if the data and files are on the smaller size like spreed sheets, taxes, and personal info.(they can resist anything except full submersion and excessive smashing. locked away in a fire/water proof safe and your good.)
more expensive would be four or five drives of same make model and size in a redundant sett up.(A bit larger, heavier, and uses more power but can give you back-up in the event of a drive failure.)
2- As I have stated before, flash drives work for smaller files and thanks to technology can hold up to 32 gigs a piece, yet TB hard drives can offer much more storage and you may even be able to back up your entire system!
3- Information LOCKED away may be safest but hardest to kept up to date. I suggest VERY sensitive info be under lock and key with fire/water protection. Yet more public info that could be easily re obtained is to be placed on any level of backup drives.