I can’t overemphasize the need to back up your work. I back up my current projects on a flash drive and on Dropbox, and then once a month I back everything for that month up on an external hard drive. Computers crash, and even if they don’t, you will most likely upgrade and not transfer all your old files over to a new computer.
Thus, I suggest always keeping a paper copy of everything. Buy a box of file folders and label them. If you are like me, you would rather write than organize files, but lack of organization can cost you precious hours of trying to locate information on an article you wrote several months or years ago.
Label one file for each project you are currently working on. Once an article or book is finished, continue to keep a file folder for it. Keep your research notes in it as well as tear sheets of publishing credits. Any research you have done for an article or book should be labeled in a manner that will help you find it quickly should you decide to write a second article or book on the same subject at a later date.
Also, set up files for ideas that pop into your mind, ones you don’t have time to develop yet. Whenever you find an article or story on a subject you intend to write on someday, place it in a file folder under that category.
I was recently looking for information I wrote 15 years ago, and it was only on a 3 ½ inch floppy disk. I don’t even have a drive to read those anymore! Thankfully I had a hard copy I could scan back into my computer.