Like most authors, step.1 is the writing... though the next steps in the creative process usually diverge into idiosyncratic methods for each individual creator.
After the idea, story & writing are done... I visualize the narrative out through 2 intermediate steps prior to pencilling my final artboard.
I thumbnail quick images from my script to get a good 'shot' of each frame. These literally take me 5 seconds each to scribble. No care in technique is taken. It's simply bainstorming ideas. My thinking on each thumb is, "No, yes, no, no, maybe, no, yes".... it's that quick a physical exercise.
When I think I've gone through the short story/arc of the script in my thumbnailing, I then start to sketch the thumbnails I think 'worked' into my sketchbook as quick final compostions. You can probably see which thumbnails influenced sketches below...
Once i start sketching like this, i often come up with even more camera angles and perspectives. The above boxing scenario was only 1-2 thumbnails, but i ended up running with it once i saw it gain form in these sketches. This process is really like putting flesh on the skeleton... visually speaking.
This sketching process is the most fun for me. You see, I have a guide (the thumbnails) to hold my hand, and so sketching the content of panels in my comic like this is an absolute joy.
I never have the fear of a blank sheet of paper.