Almost every website, piece of software, or communication protocol ever programed was written (at least in part) in plain-text. This makes it the most compatible, reliable, and flexible file-format in existence; one who writes in plain-text can rest assured their files will be readable forever by any computer ever made in their lifetime.
Because programmers work almost exclusively in plain-text they have built themselves amazing tools. With a little work one can learn how to leverage these powerful tools and customize their writing environment as they see fit.
For those who want a universal and future-proof way to store their writing, and powerful and reliable software to write in, plain-text is the ticket.
The single most important thing I do when writing, from a computing standpoint, is to put each clause or idea of a sentence on a separate line. I got the idea from Brandon Rhodes (by way of Brian W. Kernighan) and have been using it ever since. Here's how he explains it:
By starting a new line at the end of each sentence, and splitting sentences themselves at natural breaks between clauses, a text file becomes far easier to edit and version control. Text editors are very good at manipulating lines — so when each sentence is a contiguous block of lines, your editor suddenly becomes a very powerful mechanism for quickly rearranging clauses and ideas.
Splitting each clause of a sentence into separate lines more clearly highlights the structure of a sentence. Apparently, Buckminster Fuller called it "Ventilated Prose". The effect has been so profound that I now write by hand in this way. (There's even an xkcd comic about it.)