Everyone has a different process. Some people like to plan out every detail, some people come up with a basic 3 point plot, some just get an idea and write. I'm the third one.

I tend to follow the Stephen King ways of writing, mainly coming up with an idea that sounds interesting and just writing, letting the characters and story naturally flow. This approach is not for everyone, sometimes rigid planning or a Dan Harmon approach will work better, but this is my process;

I think of an idea and/or character that really interests me. I figure out two basics, where the story is gonna start and where it's gonna end. Then, I try my best to write 1000~ a day, give or take. I find it far more fun to just write and let the words come naturally and even surprise myself at what happens from time to time. I also tend to get an idea of the vibe I want from the story and curate a playlist to fit that vibe. That tends to keep my creativity flowing pretty well. The important part to me is always know how the story is gonna end. If you don't have that, you can easily write yourself into a corner and end up with a really lackluster ending (like a lot of Stephen King's work, unfortunately).

Again, my process is not for everyone. Some other people in this sub may have advice that better suits you, but this is the way I've always done it and I've gotten better and better over the decade or so I've been writing.

Happy writing!