Scripting
With Treehouse, my current project, I have a general idea of what I want to steer towards, but other than that I work in a very chapter-to-chapter based way. I usually write a loose script/brainstorm for each chapter, but it's not very strict and is often changed as I draw it. As with the general story, I will usually have an idea of what I want to happen in the chapter, but all the dialogue and "inbetween stuff" comes from my characters and how I imagine they would react to the situations I put them in.
Drawing
When I am lucky enough to have a day without lectures or a weekend with no studying, I get up early-ish, make a pot of coffee, and sit down in front of the computer, drawing all day. If I am not "in the zone", I will usually watch something meanwhile on my second monitor (currently watching the final season of Dexter), but every now and then I hit a "rampage mode", where I can just keep drawing at the speed of fast until my fingers get sore.
I will typically start by rough sketching the entire chapter, seeing if my intended panel layout will work for the amount of dialogue and action I had intended, and adjust the number of pages otherwise. Then I start jumping around between pages, doing more detailed sketches, lineart, adding text and tones here and there. If the chapter has a money shot panel (like for example third-to-last page of this), this is usually where I start (since it is the most fun to draw, hehe).
If I am not watching a show on my second monitor, I always listen to music. Depending on my mood, I listen to epic orchestral music, movie soundtracks, EDM, dubstep, classical, and sometimes J-pop.