I did a short analysis of the basic writing process (e.g. without spending items) for potentials of 20-60 (60 being the maximum potential reachable by daring edits) and persuasive of 17-84 (84 being the level at which daring edits always succeed). What I found is that for any persuasive below 54, the best way to earn echoes is simply to spend the basic actions to gather the bare minimum manuscript pages, without improving potential at all. Then attempt to publish at a competent level, which–if you have at least 17 persuasive–will net you roughly 4.38 echoes on average or about 36 pence per action at sensible paces. Of course, this barely improves your persuasive at all (one CP for 12 actions), so if you’re looking to level that, there are better ways. Writing is for starving artists.
At higher levels one may begin to expand one’s literary horizons. At a persuasive of 50, it becomes profitable to write rapidly. At 54, one may make the leap from the yellow rags to the literary journals, polishing your work to 50 potential and attempting a compelling outcome. At 63, if one so desires, an ornate typewriter may be purchased and used. Still, even with these improvements, you should expect to make at most 60 pence per action at 84 persuasive. Since by that point more lucrative ventures should have opened up, it’s probably not worth pursuing except for the pride of having written a work of high merit. For those newly fallen, however, it’s a pretty good way to earn the echoes that come so dear to them.