Save your files often and make multiple backup copies.
Nothing is so debilitating as following the first six rules and then losing the whole work to a cyber-space demon. Saying you lost your work to the computer, or that it will not print out, now runs well ahead of dogs eating homework in the excuse category. It may be true, but it is very difficult to prove and, if the TA or professor is on a tight schedule to turn in final grades, you may not get the benefit of the doubt.
Save your files regularly, especially after making extensive revisions, and when you are finished be sure to copy your files onto a separate device, send a copy to the cloud, and/or send it to yourself as an email attachment. That way you can retrieve the latest version of your paper if disaster strikes.