Is there a particular reference you're using? As someone who's not very familiar with Starcraft, it'd be helpful to see if you're working from something.

From a quick image search, it looks like the general silhouette is good. The arms, particularly the forearms, should probably be larger though.

You also have a lot of colours in there (I make it 71), many of which are very similar to each other. One of them is only used for a single pixel. You could strip a lot of those out (you could definitely more than halve the colour count) without any noticeable difference to the overall image. I also think you could boost the contrast a bit because it's looking a little flat. Zeratul looks to be quite muscular so you could really give some definition to the limbs. On that point, the brown bandages/rags wrapped around the limbs and torso should also be shaded according to the forms underneath. On the left hand side of the image, they're currently getting lighter when the thigh underneath is getting darker. You can absolutely still shade them so they have their own volume, but they should be contributing to the sense of the overall volume of the body as well.

As a final point, I think you could go bolder with the ridges on the head. They look quite pronounced on Google but it's another area where you're lacking contrast so they aren't standing out very well.

I hope that doesn't sound too negative. I think you've got a really good start here and it should be quite easy to refine it. 

Wow, that's even more than i expected, at least from one person.The colour count is huge, i know(shrinked it to 71 from initial 200+ colors. I kept that much to save that detailed gem look)
Muscles, as i mentioned in my first post, is a struggle. Can't find a proper approach to them.
Even now as i look at it myself i notice where i can get improvements and i think i will revisit it sometimes later. Now i am busy with other SC char-Kerrigan

Much appreciated for feedback, it inspires me to continue.

Posted some new stuff. Looking for work. Short term or long term projects OK.

Update

To help me set up goals I decided to compare my progress against snatcher. Made a visit over to junker hq. Downloaded the script files for sega saturn snatcher. Wrote a Python-script to analyze to code.

The (very rough) results ~:
8464 unique lines with 80148 words and 719 actions.

I planned about 20 scenes in 'on the take' so that would make it:
423 lines with 4007 words and 36 actions per scene.

Next step is too add a progress checker into the twine2renpy builder.

Recent review

"Awesome work! 10/10. Would definitely recommend/ use again! Thank you!!!!!!"

We can only comment on so much without the reference; her proportions look generally ok, the face seems well observed. Not too many colors- in fact, the hair might want a few more shades. Over emphasizing odd shapes like the neck wrinkles and chin can add to it looking "off". I'd recommend squinting at your reference, and only worrying about the shapes that still persist even through the blurred vision. This ensures you're getting the "essential" shapes right that will inform her likeness.

This is also an ambitiously sized pixel art piece! Half the size might be more manageable! Either way it's a valiant effort so far, good luck with it