I don't think much of most books about how to write and/or draw comic books. Some have been spectacularly narrow in their viewpoints, either because the author lacked even a basic range of experience or was only interested in getting new people to work the way his company then preferred. It's like if a book on how to cook chicken spoke only of frying and didn't mention that maybe there are other methods, one of which might better serve your interests and skills. Avoidance of this tunnel-vision is one reason that I like the new series of books that my pal Nat Gertler is issuing, publishing comic book scripts for all the world to see.
Another is that in the celebration of the art form, the contribution of writers is too often misperceived or just plain ignored. Yet another is that in his recently-released second volume, he has a script of mine — a plot, actually, for an issue of Groo the Wanderer. This book is called Panel Two, and it's the follow-up to (you guessed it) Panel One, which is also quite wonderful. I suspect a wanna-be comic book writer could learn more from these books than all the others ever issued on the subject. There are intros that explain a lot of the process but the true education comes from seeing how different people do it, and that no one form or approach is "correct." Here's a link to a page that will tell you more about them…or you can just rush to your nearby comic shop and plunk down cash.
I do not recommend trying to make one's career in the comic book business these days. It is not a healthy field in which to invest the kind of creative energy and passion that is usually required to break into a new line of work, and I think it will get worse before it gets better. But if you're dead-set determined to write comic books, Nat's books will show you how. Or better still, they'll allow you to teach yourself.