I'm a writer and have read various books on how to write fiction. But I'm curious about historical guides, partly through having recently looked into James Joyce's early efforts. When one reads one of Joyce's earliest attempts at writing creatively--the early essay, 'A Portrait of the Artist' (not the later novel with a similar title)--it is surprisingly poor. The prose is littered with ill-digested rhetorical devices. However, only a short time later Joyce was writing with a knowledge and mastery of fictional technique. It seems to me that during this interval Joyce probably read some books on how to write fiction. I'm sure such historical primers existed; I'm curious as to what they were.
I cannot speak for literature in general, but for pulp fiction in the 1920s and 30s, a large part of it was learning-by-doing, with the aid and assistance of a good agent or editor if you were so fortunate, and a close study of what stories that the magazine had already published to get an idea of the kinds of fiction that they wanted to publish and the style it was in. One example of this kind of "training" was discussed by agent Otis Adelbert Kline in a letter to his New York representative Otto Binder, dated 14 Oct 1936:
I really gave [E. Hoffman] Price his start in the detective story field. When he wanted to branch out he came to me, and at that time I told him I was busy with my own writing and didn’t want to take on anymore clients. I recommended [August] Lenniger. He sent him four or five novelettes and a bunch of shorts, and Lenniger didn’t sell a damn thing for him over a period of six months. He then asked me if I would check up and see what was wrong for him. I agreed to do so, and he wrote Lenniger for a couple of the novelettes. He revised them under my directions, and I sold them right off the bat to Dell for 1¼¢ a word. He then wrote for some more, and during that six months period I sold, all told, five novelettes which Lenniger had been unable to sell because he didn’t demand revisions, and three or four short stories. With all of these sales editors began to notice Price’s name, and Lenniger began to sit up and take notice. He sold a short story for Price, and started going around to editorial offices trying to get assignments. Then he sold a novelette, and some other stuff, and kept getting Price more assignments. In spite of that fact, I sold twice as much for Price over the period of a year as did Lenniger. I continued this record for another year. [. . .] Lenniger, however, kept boring in, using the assignment method. He kept contacting new editors, asking for assignments for Price. Then he would wire or airmail Price, and naturally he wouldn’t turn down any orders for stories if he could possibly fill them, on the “bird in the hand” theory. This ran down my stock of Price stories, and of course ran down my sales. I got him the Pawang Ali assignment from [Orlin] Tremain, and if I had been in New York regularly could have gotten him a lot of others and beaten Lenniger at his own game. As it is, he is cashing in on a man I trained for the work, and the only way I can beat him is through the New York end.
But even then, there was already a marketplace for advice for would-be writers. This was most evident in a number of "trade journals" - most notably The Writer, Author & Journalist, and Writer's Digest, although there were any number of others. Standalone guides to writing also existed, although were usually geared toward more traditional magazines and journalism; one notable example was The Free Lance Writers' Handbook (1927), and the cheap and ubiquitous line of Little Blue Books included such titles as Hints on Writing Short Stories (326), Rhetoric Self Taught (822), English Composition Self Taught (823), How to Write for the Market (1131), How To Prepare Manuscripts (1143). Some prominent pulp writers even published their how-to guides, such as H. Bedford-Jones The Graduate Fictioneer (1932); H. P. Lovecraft famously wrote a little essay "Some Notes on Writing Interplanetary Fiction" (1935), and "Some Notes on Writing Weird Fiction" (1937).
There also existed "schools" and correspondence courses; one such example was the Palmer Photoplay Corporation, established in 1918 to train freelance writers for Hollywood studios, but in 1924 became the Palmer Institute of Authorship, started working with pulp and magazine authors. Pulpster Arthur J. Burk famously got his start at Palmer.
For would-be writers who had the skills but not necessarily the imagination to churn out 5,000 or 10,000 words a week, there also existed "plot robots." These were systems that quasi-randomly sorted various elements to provide a generic plot - enough for a good pulpster to write to. Lovecraft commented on that in a letter to E. Hoffmann Price, 4 May 1935:
I’ve heard a good deal about those plot devices, & once thought they might be of help to me concocting commercial junk. I argued that, except for the disgust & repulsion which keeps one from devising unguided pulp puerilities, I could concoct independent synthetic crap as easily as I could tinker with the kindred crap of other would-be hacks. If, then, I had a conventional mechanical plot doped out by some external agency—which is as much & more than I have to go by in many revision jobs—why could I not do with that what I ordinarily do with the feeble conventionalities of others . . . the only difference being that I could collect all the possible proceeds instead of merely a fee? The ‘plot elements’ arrived at through these gadgets would be equivalent to a bum story offered for revision by Mrs. Heald or old Adolph de Castro or some other aspiring pulpist. Well—I got to the point of sending a dollar to one of these companies in Los Angeles (the same one, I think, which makes the Plot Germs) for something called the Plot Robot—a set of lists of stock characters, situations, climaxes, difficulties, &c. &c. &c. &. to be chosen in juxtaposition by the twirling of a pointer on a dial. God, what cheap hokum! To make matters worse, they sent a set of lists pertaining to a branch of fiction utterly & especially antipathetic to me—romance-adventure, or something like that, with noble hero, beautiful she-ro, black oily [indecipherable], stirring deeds, & all the rest. It was simply too much for my stomach [...]