Next I coloured the tongue with a light red using the airbrush tool and again I just went over the main black lines and some of the shading in a random way and this was smudged to blend the red further and then I added a large size airbrush of a light yellow to highlight the monsters face and a bright blue to give the eye of the monster a sense of evil power or something.
I also made the background black and blended all of the edges of the monsters head, so that it would look cool enough. Adding a light source to the front of the monster also helped the lens flare look more brighter and added a contrast to the whole monster design.
You can see a few more examples of my Gimp software adventures here - Gimp Art Design Software
Here's the finished drawing....