The first thing I do is plan the storyline, I do this by making a Google Drive folder, I make a lot of different docs in there…
So as I said the first thing is the main storyline, just a summary, nothing too big.
When I’m done with that I plan out my characters, first the MC, second the LI('s), third important side characters…
This is what I write down for them: Full name, birthday/age, fears, personality, romantic history, their past (childhood), and Sexuality, Gender & Pronounce.
The childhood parts took up like 1/3 of a whole page for me, since I wanted to be as detailed as possible, yet without writing too much.
After that, I planned out a few chapters, just the main things that were gonna happen.
And then I started coding/writing.
I did all these things in different docs to keep it organized, but it is just what you prefer to do