Zophia poked me to make a thread. I know this will die off quickly, but I guess I could just show off some work in progress, and what I have managed to do by combining MsPaint and GIMP.
The first one is the outline. It is done in MsPaint, since GIMP was acting up.
The next two is the coloured result, both coloured in GIMP (It was acting okay again) The difference is the outline. The upper one is with the original outline:
With this one I copied the outline and blured it. So the original outline is on top, the next layer is blured, and then the colour come:
The last one here is what I will think of as the conclusion. A gradient layer from GIMP, smudged out and adjusted, again with the smudge tool. The lazy solution, I know.
Work in progress, right? I do not know if I am going to make it any better.