Just as there are many different styles of art, there are many different styles to creating a story.
So you know where I'm coming from, I write my comic without plotting in advance, I don't have a storyboard but a bunch of plot-points to carry myself along. There's a term for this in writing actually which is "Writing by the seat of your pants".
It might seem like a very unprofessional way to go about this, but there's actually a good amount of really successful writers who use this style of writing, like Stephen King, and J. R. R. Tolkein actually wrote Lord of the Rings this way.
A bit of digging around the internet can probably unearth more, but my point is that you should use what works for you, there's no "right" way to do it.
So plan everything in advance if you need too, or write the whole thing as you go, it's more about where you go rather then how you got there.