Here's some random doodles of a bear character I had rolling around in my head. Lately, when I draw I prefer to use Polychromos because it's an erasable pencil and it has a nice flow. Years back when I was working on Mighty Mouse: The New Adventures For Bakshi & John K. and Beany & Cecil for John Kricfalusi, I was used to drawing in Col-erase, however John quickly got me out of that and told me to draw with Prismacolors for my character layouts. Prismacolor Pencils have a nice flow and you can get a drawing down pretty loose and quick, but the main problem is that they're nearly impossible to erase with! In order to correct the drawing, you had to use white out. I got used to drawing with those pencils and still like to sketch with them as seen here with the bear heads. My approach with Prismacolor is simple; I'll do a very light underdrawing first, then go over it with bolder strokes.
Most of the time though, I'm using Polychromos or Ebony pencils for my sketching, but will still switch back to Prismacolor for fun or col-erase for animation work.