This is one of my sketchbooks that I carry with me everywhere along with my travel-size Windsor Newton watercolor kit. With a cheap black Bic pen to start off my sketch, and with the help of the wonderful mid-value paper, I was able to create some creatures that are still some of my favorites till this day. A little trick for making your sketchbook illustrations more vibrant is to later use Gesso for the highlights and then once dried, apply a thin layer over it using Acrylic dyes increasing the vibrancy ten fold.
This next one is a character design sketch, using black prismacolor pencil, watercolor and gesso on a bristle paper. I also use a 9 h pencil for the designs on the vest and a little airbrush to enhance the overall form and shape of our little guy. Gesso works great for the highlights and with a little water.