Not sure about books specifically, but I'd suggest you just look over at /lit/ and find something you're into.
Also some other tips based on my own experience both reading and writing a whole bunch of stuff (part of which you may already be familiar with depending on your experience):
* No, unless you turn out to be an absolute fucking master at descriptions, good style/language is not gonna make up for bad anatomy. Obviously these are stories for entertainment purposes, so some degree of artistic license is fine, but I highly advise against approaching the whole thing with this mindset. (Depending on your specific subject) Just a couple of minutes on wikipedia or so will suffice to give you a general idea about most types of injury/death so you can avoid the more egregious mistakes.
* I find that for (guro) erotica description trumps over narrative. Sure, some framework plot/setup or characterisation is nice too, but the detailed descriptions of the action and the character's feelings in that moment are the main draw, imo. Unless there's something very specific long-form you wanna write, I recommend sticking with short stories (as in, the literary genre, not the word count).
* Closely related, those descriptions. You want to be detailed/accurate, yet (relatively) concise. Avoid describing one single thing with half a dozen adjectives; instead describe several relevant things (if applicable) more briefly; to that end pay attention to all senses or surroundings. Try not to overly repeat yourself, but don't be afraid of sometimes reusing the same word a few paragraphs later; better that than to desperately search for new synonyms and end up with a bunch of rare/arcane adjectives that just scream 'thesaurus'. Honestly, good descriptions are probably one of the trickiest parts if you ask me, and this one really is probably better learned by reading a bunch of examples.
* Choice of words. This is a pretty big one in erotica (and may actually be worse in books rather than stories posted online), do NOT use dumb euphemisms to refer to sex or genitalia, it's never anything but cringey. You're still writing a story about people fucking, so just say that they're 'fucking'. And while you don't have to be as vulgar as you can (which is why I personally hardly ever use the word 'cunt') be to the point describing those things. A guy has a dick, cock or penis, not a 'member', 'organ' (which one, his pancreas?) or 'manhood' (though this latter one may get a pass if the whole story is written in a kinda archaic style, perhaps). Similarly it's pussy, cunt or (sometimes) vagina, not 'folds', 'depths', 'womanhood', etc. Also note that the language you write in should be language your PoV character(s) use. So if one of them would actually speak/think in those euphemisms, you have somewhat of an excuse, but don't overdo it. And if the character would be completely blunt about it, then so should your writing.
* This one should be obvious (and will be if you've done any real writing before), but you'd be surprised. Use fucking spellcheck. Keep your tenses consistent through the whole story. Use paragraphs both for dialogue and to break up huge blocks of text. Re-read the whole story, slowly, to catch any other mistakes; or better yet, get someone else to proofread it for you. Spelling/grammar errors or just an unreadable style/layout will turn people away before they even give the content any chance, regardless of how good it might have been.
Hope some of this is helpful, feel free to ask if you wanna know anything more/specific.
I don't see any very specific issues with guro stories that do not apply to all other literature. Even original Red Riding Hood is a guro story.
Maybe one thing after all: Since guro usually is about things that do not happen in real life very often or just never at all and you do not see them on TV It may be hard to imagine or understand what you are describing.
this is especially problematic for size references Like how we are supposed to know what is the size of that gargantuan cock which still somehow manages to fit in the vagina of the little girl? so you need to take extra care in describing that stuff.
If you worry about internal anatomy I guess your story will turn into scientific thesis anyway just use plain medical terms. If you worry about external anatomy I think this is not guro related.
You were very through, thanks. You said that the best way to learn is reading examples. I agree, most people write by osmosis. Where can I find the best examples, though? Just /lit/? Is there any story repository?
There's probably some literature section on like every guro/'dark' forum (FetNoir, Dark Fetish Net, etc), but I've never much been to any of those, so I can't speak for the quality there. But /lit/ (including a pretty lengthy thread by yours truly, even if it's past the bump limit and I haven't got to updating in a bit) as well as some threads in /rp/ (the prompt-based short story ones, such as the stickied Killer/Victim and Finish Her and their derivatives; though the quality …fluctuates) is a good start There's also a relatively new subreddit of /r/deadlyerotica/. Just go and check out any of these, you're bound to find something.
Keep an eye on rhythm and phrasing–yes, rhythm isn't just for poetry–and try to make it so it could be interesting even if someone weren't reading it for the fetish content. Avoid onomatopoeia and excessive descriptions not related to the erotic or plot focus–aka don't spend more than a couple sentences describing someone's clothing unless it's integral to the fetish content or important to the plot. If someone's getting strangled with a belt or using it to escape from a peril, it's okay to describe the belt. Otherwise, something like "she was wearing a leather belt" is enough. It's infuriating to readers when they click on a story and it looks several paragraphs long, only to find that the first 4-5 paragraphs are describing perfectly ordinary clothing and only the last 2-3 have anything to do with the fetish. (Google "asstr bad curry" if you want an example of this kind of mistake.) Onomatopoeia is bad because the readers have to read each character instead of just recognizing most of the words, and because readers don't have any emotional associations with random strings of vowels. It's almost always much better to describe the sound than to repeat it. Say something like "Jen screamed shrilly," not "Jen screamed 'AAAAAAAH'." If you have to use it, keep it short: "Sally let out a soft 'uhhh' and collapsed to the floor.'" Long onomatopoeia can also break text width on some sites, or on phones. In general, it's just rude. You can do better.
Make sure to use enough punctuation. If in doubt, try reading it out loud, making sure to only pronounce the punctuation that is actually there. A comma is a connecting pause, em-dashes are a longer connecting pause, and parentheses are kind of a combination of the two (usually used when an inserted phrase would be distracting otherwise). These things are all for separating phrases, as well as clauses if a conjunction such as "and" is used. Commas are also for separating different items in a list. A period ends a sentence. It is a pause, but also means the pitch of the last syllable before it is usually lower, indicating resolution. A semicolon connects two things that could be independent sentence, but which have ideas that are very closely related; many people make the mistake of tying "independent clauses" together with a comma, but unless you use a conjunction like "and" or "but," you need to use a semicolon instead. Colons are for lists or summaries. Quotation marks are for dialog, quoting, or definitions or examples. If you are ending dialog but adding something like "he said" after it, the last period gets replaced by a comma, but other punctuation isn't affected.
There are also lots of style guides available on the internet. Look up "style guide" on google and follow the recommendations until you know what you're doing.
And yes, read stuff. Don't look for traditional books. Don't look at /lit/ either, because honestly most of it is something to be improved upon, not emulated. Archiveofourown.org would be where I'd point to, because it's got really good content sorting and also will let you sort all works tagged with "gore" by the number of "kudos" or likes they have. Though popular approval isn't completely foolproof, if you filter for single-chapter gore or guro fics in English that are most liked (yes, you can do that, AO3 is pretty much the gold standard for archive design), you'll get a good sampling of stories that are written well and can be emulated.
Exactly what Eterya said.
As someone into elaborate torture machines, I find concise descriptions to be the battle to prioritize. It's been my greatest source of stress for good reason.>>8731
LOL! yes, original Red Riding Hood is about a wolf eating a woman and pretending to be her then getting chopped up by a woodsman.
Read erotica to learn erotic language. Read crime (or action) thrillers to learn violence.
I don't recommend /lit/ as a primary resource because stories there so often fail at basic writing mechanics. Some are fine, but prefer professional (or at least proofread) stories.