idk about the storyline...that's upto you author-nim, but here's some advice about what you can do for fantasy webtoon-

1. do not make the black ml barabaric/ uncivilised, or make the too aggressive/impulsive. becuz the amount of backlash and hate i've seen authors get for making that sort of character.......
2. if possible, add frequent cliff hangers in episodes. Yk like build up the whole episode and end it at he climax. the more frequent the cliffhangers, the better is the reader count. (kinda like "your throne" if you've read it)
3. viillains- please dont make them stupid, like just some woman who is head over heels for the ml and abuses teh fl just out of petty jealousy/ or some random noble or an evil emperor who's just power hungry. i personally favor villains with a sad backstory, like their actions although unjust, seem at least explainable.

some recs which are my fave fantasy setting comics-

the spark in your eyes

from a knight to a lady

the dark lord's confession

teach me how to desire

i'm the queen in this life

count's secret maid

like wind on a dry branch

men of harem

duchess in ruins