Looks like a good start
Anatomy might be tuned a bit (pun intended). Although that's not necessarily an issue, the lower body is pretty long compared to the human half, I don't know if it's biology, perspective or both. Her right arm looks more like a tentacle, I guess you just roughed it out so far or else it might be a deliberate choice too.
I don't understand the body shading very well, as it seems that her body has color variations that override shading? That might complicate things, esp in the human parts. Bright tail fins read as transparent: that would be nice.
No idea what the dark things on boobs and pelvis are.
Colors do look a little bland, widening the hue range would help.
Here is a nice underwater palette if you need inspiration!
Dithering and texturing and scales: look at how others did it. Bear in mind that it's about suggesting rather than showing: you can't possibly draw each individual scale and it would be pretty boring if you did. A good rule of thumb about dithering: the less there is, the better!
Here's one nice mermaid with careful dither-texturing that evokes sparkly scales just the right amount.
Alternatively, look at
this incredibly wet and leathery dolphin skin without the slightest amount of dithering.
More examples.