This is some of my 2D work. I usually use a blue pencil to sketch things out first. Than I ink it and lay the the tonal values with grey markers. Some times I add shading with a simple 3B pencil in order to give more depth. Highlight are done with a white pencil and white acrylic paint.

Later on, things get colored in Photoshop and/or Painter. Sometimes I color things traditionally using watercolors and color pencils. But mostly I prefer to do it digitally since it's faster and I have the luxury of the "undo" button :).