The shape is pretty good, but what program do you use? With any, I suggest either shading in lines with white, coming out from the pupil and hitting the edge, then making it 50% transparent if that works, or doing the same thing with a very close but a bit lighter or darker shade of the blue you used for the eye! Ha, long comments.

I used MyPaint, I kinda switch between that, and GIMP.

ahh, I use Gimp. If you use the airbrush tool with white, it works well!

I can really only draw halfway decent on paper, but when I use my tablet for digital art, I suck.

Naww, your doing fine! Some people make a sketch on paper, and put it on their computer. Then, since you have gimp, put a layer over it and make the lineart there!

Ah you haven't seen mine.

Constructive criticism, eh? Let's get started!

I really like the shading on the iris, it looks soft and watercolor-ish.
But for some reason, the black specks bother me. They look very... sharp, in contrast with the rest of the iris. Some advice here would be to either get rid of them (although I assume you put them there to add a little more realism or so the iris doesn't look to empty) or try to adjust transparency of certain groups of them so that they appear to blend a bit more with the rest of the iris.

And another thing is that the bottom-right corner of the eye (in reference to the actual image, not to what the eye is seeing) seems out of place, like it goes out too far.

Other than that, this seems well-drawn. I look forward to seeing more of your artwork in my inbox!