I have to ask! What kind on colouring pencils/tools you use on your traditional drawings? The colors seem so vibrant even though the paper apparently is gray(?), and the whites and other bright colors stick out so nicely. I can't get the same results with any regular colouring or pastel pencils...
I use mechanical pencils with color mines at the first stage of the drawing, then pens, pastels and sometimes watercolor. I always finish with digital drawing (wacom tablet & Photoshop) to add more contrast, change colors etc.