Willowtails

I guess I just have to grab a sponge and start trying some stuff out and keep practicing then. Thanks for the answers.

First post. Have found a lot of useful info in these forums, but now I came across something that I can't seem to find the answer to. I found these pictures, and I really like how they painted this, but I can't figure out how they did it. All I know is they did it all by hand, not airbrush. Can someone explain to me how to achieve this? Thanks in advance. Tom