A little bit late, but here's my two cents:
According to some manga tutorials book I've read, there are several ways to draw manga/make story. And different people could be more comfortable with different way. Just find the one that work the best for you. These are some way that's described in the book (and I believe it's not limited to these)
1. Draw from imagination
2. Make storyboard
3. Write important points and then sketches
4. Write a full paragraph of the story
Personally, I use number 1. But for difficult scene, I switch to number 3.
okay thanks...i really appreciate the help.