I'm a huge fan of outlines. I'm gonna include a video where some simple methods are explained (you don't have to watch it)
But If you do watch it, and you like the method, you can go deeper, google search and check concept that are extremely important for storytelling and keep the readers attention
Concepts like: Introduction, pinch point, middle, pinch point, climax, resolution... And also basic rules for a story to be good. How to make believable characters, to know what you want to convey to the reader, etc. You can check an awesome book called "The foundations of screenwriting" by Syd Field. He revised tons of scripts for movies and was kind able to predict which ones were going to be a success while others were going to fail
There are people that don't like planning their comic at all. I used to be one and created around 40+ stories... they're not as good as the ones I have made an outline or/and script for. Then again, it depends of each person's creative process
There are also tons of books about the subject and If you really like creating stories you will probably find them extremely interesting.
That's only the writing part of course. Storyboards are another subject. For those, may I recommend "Understanding comics" by Scott McCloud. It's a book on comic format about comics. It's so good.
For discipline and beginner mistakes, you can read "On Writing" by Stephen King.
Maybe those may seems like many books for some people. I just love getting better and learn from mentors a bit faster rather than reinventing the wheel and making even more mistakes myself.
But I understand If some people... Just will go with their gut and that's ok too ^^