Colour Pencil Once Again

Today I did a colour pencil drawing for my drawing homework. It took me 3 hours to complete, and yet the results are still not quite satisfactory. I just don't understand how some people can have such saturated colours with mere colour pencils (yes I'm using chromatic greys only); maybe simply because I'm not pro enough, or that the paper they used is more suited for colour pencils. But I think I'll just leave this work as it is, for I still have another piece to draw. If I were to spend more time on this piece, I don't think I can finish my other one, and certainly no time to finish up all my other homework!