If you have edited and erased large sections that you later wish you could go back to, a version control system may be useful to you. Version control systems retain old versions (very efficiently with plaintext) and allow you to easily access earlier versions and to compare versions (of plaintext) easily.
There are many flavors. You can use one totally on a single machine, but with the Internet widely available, with traveling between multiple machines, and with other possible remote collaborators, a better system is likely to have a repository online. A very handy option in http://bitbucket.org. It allow free access for higher ed users with any number of private contributors, and you can chose a repository to be publicly viewable or not.
If you are collaborating, you will want to upload your changes frequently, so your collaborator has your latest work. Even if you are not so conscientious, if you are working on separate files, updating is immediate, and even if you make simultaneous separate edits to the same plaintext file, comparison and merging changes is facilitated.
Bitbucket allows two version control systems, both free downloads. We have been using Mercurial and there is also git. The basic Mercurial client work from the command line, but if that is foreign to you, there are also graphical, mouse-driven interfaces for most operating systems and now mobile apps.
The source files for this presentation are at https://bitbucket.org/gkthiruvathukal/fotl.