As the Kindle's dread grip on digital publishing is challenged by tablet computers and Android smartphones, with their bright screens and high resolution, the need for illustration is growing.

Do you have hands? Excellent. That's a good start. Can you hold a pencil? Great. If you have a sketchbook, open it and start by making a line, a mark, wherever. Doodle.

I'm not a painter by any stretch of the imagination; I'm a dyed-in-the-wool traditional illustrator, and I begin with black and white. If I need colour, I add it over the top. There's a calligraphic element to it... it's about the texture of lines on the page.