I have recently found a drawing of Ariel I did for fun a while ago and I thought it was a good idea to publish it.
The original sketch is by artist Glen Keane, the colored version is mine.
This has been made in Photoshop. To accomplish this result I set the opacity of my brushes at a low level. This way when the flow of the same color crossed (water versus deeper water/shadow) it gave a feeling of watercolors. When two different colors crossed (like hair and water) they gave the impression of dirt color, which I think is more realistic than a perfectly colored drawing.