Woohoo! A topic I know a little bit about...
You seem to have this covered already based off your post, but paragraphs are important. No one wants to read a wall built from words. I know that seems like something really basic but, as you've no doubt seen for yourself, plenty of people still post stories that are a single paragraph.
In terms of the "HAHAHAHAHAHA" I think it definitely has it's place. Personally I tend to try and mix it up, a lot of description, a but of "HAHAHAHA". The trick is doing the laughter in a manner that doesn't seem ridiculous, lines and lines of nothing but "HAHAHAHA" is just silly. No one's going to read every single "HA" and it does nothing for the reader anyway. But something like "AHAHA! Oh no! PL-PLEHEEEESE!" might work a little better.
The most important thing I'd like to stress is, describe your characters. There is a common technique in many, many modern novels (The last 20-30 years) where the author won't describe their character's appearance at all, or very minimally "He is tall". Personally I don't believe this is a good technique when trying to write erotic fiction (which isn't to say it can't ever work, just that it doesn't very often). As with any story you want the reader to be able to create as vivid a picture of what's happening in their mind as possible -with erotic fiction, that picture is primarily going to be your characters. No one reads erotic fiction to find out what kind of house Mary Sue Ticklish lives in, they read it to see Mary Sue Ticklish get all hot and bothered.
Not as important, but something I try and do personally, is describe the character's early on. Sometimes the story just doesn't allow you to do it right away and you have to wait, or you don't want to do it clumsily "Mary Sue walked in, she was 5'9, blonde, long legs, wore size seven black boots with a blue tight shirt and also she had green pants" sounds silly. It's an information dump and it can be challenging to get the information across in a natural way. Sometimes you might need to spread that information over several paragraphs. The benefit of describing the character's early on in the story, is that most readers won't develop their own image. If a reader develops his or her own image of a character who's tall, slim and has black hair, then finds out halfway through the story that the character is actually short, fat and has a bright red afro, it's going to be almost impossible for the reader to change the way they view the character.
I feel like I'm probably telling you information you already know and I apologize, mostly I'm just excited for the opportunity to discuss writing technique. That said, I'll also add: Be descriptive. "John tickled Sally's feet for ten minutes and then tickled her armpits". Boo, hiss. That sucks. So he tickled her feet for ten minutes? Awesome, but what happened in those ten minutes? Did Sally sit there and read a magazine, or was she going berserk? How was he tickling her feet, did he stay in one spot, did he move around? Was it light tickling or rough, did he find a particularly bad spot and stay there, or was he nice about it?
I hope *some* of that is helpful. I'm not even entirely sure it's what you were looking for, either way I wish you the best of luck with your story and look forward to seeing what you come up with! 😀
