Wyo_girl has written a fine and very useful article on the choice of words in erotic description. It was so good that I felt moved to reply and add a few thoughts. Also, she misses a couple of important points and I wanted to suggest a few more "thesaurus" entries from my own repertoire – for the use and convenience of the young, as Oscar Wilde might have put it.
The points on word choice are
1. The choice of words ("cock" versus "hardness", say) needs to reflect the normal speech patterns, motivation and mood of the character who is speaking or whose viewpoint currently dominates the narrative.
A dominatrix talking down a slave will refer to the slave's cunt, not her sex or pussy, and certainly not her genitalia.
The same slave will think of her "sex" until she submits, when it becomes her "cunt", thus showing the progress of her mentation from paragraph to paragraph.
A chauvinistic guy with a limited imagination might say "love tunnel" or "honeypot" but I can't imagine a woman or an educated or sensitive man ever using such dreadful clichés.
A character with even a mild sense of humour may refer to the lingam as his "pork sword" or use a phrase such as "pointing Peter at the prickpleaser" (note the use of alliteration. Alliteration, incidentally, is not the same thing as writing: fuck me, fuck me, fuck me!)
A young, innocent girl might use "spear" and "sword" or even "thing"; words from her everyday vocabulary that are similes or euphemisms for the fearful tumescence she is gazing upon for the first time. She would not use a word like "hardness".
Women will usually only use "cunt" once they are in a very intimate relationship with the person they are talking to or if they wish to shock the listener/reader or emphasize their own readiness to face their sexuality head on.
Men tend to know a lot of word for the penis. Women more often stick to one or two, such as prick and dick.
Use of latinate anatomical terms (penis, labia minori) suggests that the speaker/viewpoint owner is educated/cultured.
2. It is important to vary the words to avoid a sense of repetition. This applies equally to words that do not concern anatomy or coitus. Fowler, in "Modern English Usage", calls this "elegant variation".
Rather than ‘She was too scared not to suck the monster at her lips; she was dog tired too,' (two too's) try something like ‘Fear prevented her from not sucking the monster at her lips; she was dog tired too,' or ‘She was too scared not to suck the monster at her lips; she was dog tired as well'.
On the other hand, sometimes you want to set a mood with repetition. E.g. "She came and came and came; and then, just when she thought she had no coming left in her, she came again – gloriously."
Finally, I rather dislike the use of words that appear nowhere other than in, for want of a better word, porn. This sentence is from one of wyo_girl's stories but she's by no means the only offender.
"Make me cum. Suck me til [sic] I cum, please... aahhhhh, fuck me," she begged.
I hate "cum" used like this, common as it is on this site and although it is in the dictionary these days. IMHO, that spelling should be reserved for expressions like "their guestroom-cum-dungeon". There is nothing wrong with shooting a long jet of COME over her tits. Otherwise, how can you write this:
‘Did he COME, Inspector?' ‘Yes, he CAME all over her breasts'?
"Came", past tense of "to come"; get it? If you go for the "cum" option then I think the past participle should be "cummed". You really wanna write "he cummed all over her breasts"?
Curiously, although there are several books on punctuation, there is no book available that deals specifically with punctuation for writers of fiction. In experimental fiction there are no rules, but some publishers have standards (which they usually don't publish). Here are some rules I've had to learn the hard way.
1. Comma before named addressee
‘Make me scream, Kylie.' – An order or request addressed to Kylie asking her to give pleasure (or pain) to the speaker.
‘Make me scream Kylie.' – An order or request addressed to somebody asking them to force the speaker to shout out Kylie's name.
Lots of people get this wrong, the most common examples being ‘Yes Sir', Yes Mistress', etc.
2. Capitalize proper names and titles
‘Yes, sir.' ‘Yes, darling.' Yes, my Darling.' The Master spoke quietly. ‘No, master.'
‘Yes, Sir.' ‘Yes, Darling.' Yes, my darling.' The master spoke quietly. ‘No, Master.'
There will be some borderline cases, where you must use judgment; e.g. should it be ‘Of course, Sweet Thing,' or ‘Of course, sweet thing'. It depends on whether she's just being a sweet thing or whether he's giving her the nickname Sweet Thing.
3.Comma after introductory phrase/clause
"So, you're going to help me?" is sometimes (usually) better than "So you're going to help me?". It provides a nice pause; the speaker can almost be SEEN cocking her head or smiling between phrases. But don't overdo it. Here's a sentence where I would leave it as it is. ‘This time I'll take a rain check.' Whereas a purist (such as an editor at The Newyorker!) would want ‘This time, I'll take a rain check'. It all depends on the speech rhythm you are trying to convey.
Grammar checkers are good at picking up on this kind of thing. But it must be YOU that decides.
4. Hyphenate adjectives not nouns
Her still-wet sex. His oh-so-obsequious manner. Those cunt-wrenchingly beautiful breasts of hers. Her badly applied makeup. His modest jock strap (jockstrap is OK too). Her tight tee shirt and miniscule G string. (Teeshirt is OK. G-string is usual but not really kosher. It will probably survive because the correct form makes it sound like she's playing a miniature violin.)
Her still wet sex. (Unless you mean it isn't moving; a wet, stationary target for his thrust!) Her badly-applied make-up. His modest jock-strap. Her tight tee-shirt and miniscule G-string.
5. Mandatory punctuation before closing quote
‘Did he?' she asked.
‘Wow!' breathed the boy.
Those two make sense of course but what about this?
‘I'm finished' he said.
The speaker's sentence ended with a full stop but the convention is to use a comma, because your sentence hasn't yet finished; like this
‘I'm finished,' he said.
The comma here performs no function. It's crazy, but the convention has been fixed at least since Samuel Richardson used it in "Pamela".
On the other hand, the logically and grammatically correct
He said: ‘I am not the "man" you are looking for'.
is usually written without the colon as
He said ‘I am not the "man" you are looking for'.
BTW, in American the final full stop can't be where I've placed it (correctly in English). US style rules would render the above as
He said "I am not the ‘man' you are looking for."
For me, I still use the colon, but sparingly. It is also correct to use a comma (viz. e.g. Richardson again)
Finally, a couple of additions to wyo_girl's mini thesaurus (just for fun).
Breasts, areolae and nipples
Baby feeders, boobs, cleavage curtains, knockers, secondary sex(ual) organs, squeezables, tits, two little boys fighting in a sack. Fried eggs, moon craters.
Adjectives: bud-like, burgeoning, incipient, touch-tempting, Partonesque (my own coinage), pendulous, pneumatic, scrawny, hag-like.
Arse/ass, behind, bum/butt, buttocks, derrière, fanny (US), fundament, globes, gluteus maximus, hindquarters, nates, posterior, rear, rear end, rump, seat. Anus, rectum, rosebud, the cacky chute, where the sun never shines.
My favourite adjective here is "calipygous" (= fair buttocked). One is less likely to get one's face slapped if overheard, compared to ‘Nice arse!'
The (primary) female organs
Centre of _____, fanny (GB), girls' bits, honeypot, sex, Lady Jane, Lulu, that thing you're sitting on, yoni. Labia (majori/minori), (sex) lips, those other lips, vulva. Clit(oris). Vagina. Cervix. Womb.
The male organs/genitalia
Family jewels, the future of Britain (America, Canada, the world – as appropriate). Ballbag (that's what Rabelais calls it!), bollocks, scrotum, sperm factories, the wrinkled old family retainer. Dong, erection, John Thomas, knob, lingam, member, phallus, priapus, prick, old codger, old man, one-eyed trouser snake, shrew tamer, shaft, spear, stiffy, todger, tumescence. Glans, head, helmet, tip.
Come/cum, gift, jism, load, mess, semen, spunk, white stuff. Apotheosis, climax, peak of pleasure, le petit mort, completion.
I'm sure there are lots more; but I hope these start you thinking and inventing. Get writing!