Sometimes when I sit down to do a painting I'll have been thinking about it for some time in my head about what I want the subject of the painting to be, what type of setting and lighting etc. However for this particular painting all I knew was I wanted to do a picture of a Mermaid. I start in my sketchbook working out a few pose ideas, VERY loose. At this point I don't even know what type of setting I'm doing, I'm just concentrating on the figure. I wasn't liking where this was going, so I took it even more basic and did some quick compositional thumbnails, from which I was able to select a general "mood" for the subject.

LINK:
http://www.3dtotal.com/team/Tutorials/mermaid/turningpoint_01.asp