Welcome to the forum and so good you feel taking this big step!
Welp, first of all I would recommend start with a small project, something that doesn't take you more than a 10 chapters, and each won't take you more than 20-40 panels.
Why?
Well, you'll need first to adapt to the format, regardless if you read several series, how comfortable you feel drawing in long canvases or having to cut each panel/image to place it vertically for the easy reading.
Then, this is going to be the most unsatisfying advice ever, but avoid focusing way too much if you like what you finished, finishing a page or a chapter is way more important than if you like the artstyle, you're definetly not gonna like being inconsistent, having messy pages, or the coloring, or the passing, angle, anatomy, perspective, backgrounds etc.
A lot of the time, you'll learn on the go, you didn't like how a panel was? All right, I'll try making the next ones better.
Another thing that'll probably help you lots especially if you don't want the story to be rewritten or changed (Still is something that's gonna happen, you're going to change things as you go)
Is to:
- Write an argument of the story (start to finish, this one is for yourself)
- A small summary (This is to conceal the focus of the series)
- Write your chapters (script), you don't need to focus on so many details but try to focus on writting down what you'd like to be drawn, it mostly acts as a reminder so you know what to draw.
- Do thumbnails, thumbnails are small rough sketches, like storyboards that'll help you visualize what is going on in your story/chapter
- Sketching the pages, by following the script and the thumbnails, you can have more defined sketches here, basically preparing your drawing for the inking/lineart and then coloring (Steps may vary depending on digital or traditional art)
- After finishing the pages, then you can put the dialogues in clean speech bubbles, sound effects and such.