One thing I would love to see—and which I can only assume exists—is a guide like this, tailored to writing prose rather than code. This article maintains certain assumptions that are held by nearly every other guide, like 'You are always in normal mode, and only enter insert mode for short bursts of typing text, after which you press <Esc> to go to normal mode.' Which is true and useful for coding, but slightly less so for prose—not entirely less so, and it's still a good idea to get in the habit of busting out of insert mode when you've finished whatever thought you're writing down, but the lines between thinking, composing and editing are blurrier than in prose.
Nevertheless vi controls can be pretty semantic, and lend themselves pretty effectively to working with words, clauses, sentences, and paragraphs. On the other hand, using search for mid-paragraph navigation is an order of magnitude less efficient in prose, when you're so much more likely to have symbols and words doing totally different things in many places in your text.
Here is a 13 page guide specifically aimed at writers using Vim or Gvim. Explains how the movement commands change with soft wrapping of lines and so on.
Thank you keithpeter and keithpeter for those two links.
A minor thing that's useful if you stay in insert mode for long periods: You can click the mouse anywhere while in Insert mode, and your cursor/insertion point will move to where you click. This works in Gvim, and also in vim, but I suppose vim depends on how your terminal is set up. I've done nothing special to my terminal or my vim.
Use Ctrl-o in insert mode to dip into normal mode for just 1 command. Also, use Ctrl-r in insert mode to paste the contents of an arbitrary clipboard (Ctrl-r, a to paste register "a, Ctrl-r " to paste register "" and so on).
Nevertheless vi controls can be pretty semantic, and lend themselves pretty effectively to working with words, clauses, sentences, and paragraphs. On the other hand, using search for mid-paragraph navigation is an order of magnitude less efficient in prose, when you're so much more likely to have symbols and words doing totally different things in many places in your text.