Dialogue is so important for all writing- make sure it sounds natural and somewhat individual to the character (so they aren’t all talking with the exact same patterns). figure out individual behaviourisms that you can include, both in dialogue and in descriptions, it will help with your characterisation — with fic do this through observation but if you’re creating individual characters you can have fun and experiment with the vibes:) so examples of that would be how s always tries to squish himself smaller— or in dialogue how dr34m uses his little filler words.
I hope this helps it’s just a couple of little things :)
And obviously the most important thing is to have fun and just write what you want to read- otherwise it will become stressful and more of a chore than a hobby.
Thank u so much for asking it means a lot that u would want advice from me :)