Well, it's an awesome look for scales but it doesn't quite fit the normal ideal mermaid, with the fish scales. That is more like reptillian scales, which adds more originality, but I can see how they're harder to make detailing. You're doing really well so far, but your shading seems to be opposite to what it should be in my opinion. Still, only mine.
Oh this one escaped my attention.Somehow I did not recieve this one. I have no idea how to draw at all, so can offer no advice. Looks good to me.