Well the thing about stories is its descriptive. It's good to convey what you're chracters are thinking. So definitely be expressive about it. If you have to curse then so be it. There are situations where something can be appropriate so I encourage that.

Also, just NEVER EVER do the OC's name: is blah blah and write their conversation unless it's a text msg or something. Like I'm sure you don't write that way but yea I just wanted to share a great pet peeve of mine hahahha. Another pet peeve of me and my friends share when it comes to reading fics is the usage of romanji words. It makes your writing less professional (well if you want to make it look professional that is). Just like what I stated earlier, certain things are appropriate in certain times. I don't see the use of writing a romanji word to EVERY next/few sentences. It makes the writing utterly childish. Like if it's a scene where it's serious and some wrote down "mwo" it ruins the mood of it. Your readers are not Koreans. Sure your readers may understand some but not fully. A reader did not sign up for a Korean lesson they signed up for your story and to read it. And sometimes the romanji are spelled wrong too. So don't put a language that you're unsure of in your writings. Avoid anything that you're unsure of. It'll just result to a confusion for your readers. Also, you don't have to write stories with words that are big. Sometimes those words don't express well as you have thought it'll be. So just pick words (even it's simple like big, small, nice, etc.) that you're very familiar with. So yea don't throw in random words because you think it'll fit and flows with your sentence well. Make sure it'll fit the meaning of that sentence not how it sounds. You can think about that later.

Hello ^_^
I find that putting a lot of descriptions of what people are doing while they're talking helps. It gives the reader something else to focus on in addition to the dialogue so it's not a ton of information about one thing all at once (which can be rather dull), and also spaces out the sentences so they're more visually appealing. Be sure not to make the descriptions super long though; your reader could get distracted or forget what's being talked about. Try to find a nice balance between enhancing the background of the scene and keeping the reader focused on the dialogue
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Hope this helps, feel free to contact me anytime with any other questions or if you just want to talk

I was wondering about that too...i'm sorry i wish i could help you, i'm still learning