Also it helps to have a book where you have drafts which are basically rough notes on what the chapter is about, for me I feel there are three kinds of chapters: main chapters, continuation chapters, filler chapters
Main and continuation chapters often follow the main plot of the story while filler chapters although they also follow the mains story are more so to add volume to the story and could give a chance to shed more light on side characters or side events of the main story.
You'd have to read a lot of manhwas to get a feel of the kind of plot you want, do you want a quick romance or a slow burn or no romance just platonic relationships. Does it have depressing or comedic tones etc.
It's alright to get inspiration from other manhwas as long as you aren't just outrightly copying them, if we're being honest manwhas from certain genres are essentially polished copies of each other