Some time ago i have prepared a step by step of the painting process of  bust eyes, it is Kazhatdram from the brand Galapagos Miniatures. A brutal bust modeled and painted for the box art by Ju-Won Jung.

I give you the names of the paint brands i have used:

LF: Life Color
VMC: Vallejo Model Color
CC: Citadel Color (All are from the old brand, you could find an equivalenci chart here)

After the well known of preparing, sanding and cleaning process I began to mount the figure, i attach as many pieces as i could, looking after of what can disturb and what not, then i let a part the whole standard, the sword row and the helmet decoration. I print the bust with Flat Black LF.

The first i do is to give a base coat which covers properly using Deck Brown VMC. Normally in busts i use to use a lighter colour maybe white, but it is an orc, and i want a “dirty” sclerotic.

After that i do a shadow with black and Chocolate Brown VMC in 1/1 propotion, the mix will be applied in three zones changing the dark. To do that i watter the colour and, with the supperposition of different layers, I achieve a darker o lighter finish letting the base colour more “untouched”. The first zone which is common on the two eyes is the top part of the eye ball, that will be the most dark. The second, common on the two eyes too, will be the inferior part of the eye globe, it will be less darker than the previous. The third and last is a subtle shadow in the left part of the ball (in the left eye it is wich is in the end of the eye, in the right one it is nxt to its lacrimal). All of that is done with the care to let a little zone untouched of the base colour, that zones will be exactly the contrary of the last shadow explained.

Now i paint the inside of the down eyelid and lacrimal. I do a mix of: Violet Red VMC, Brown Sand VMC and Red LC in a more or les 2/1/1 proportion. I give a coat leting the crevices in black, i watter a little the paint and blend a little that black zones getting a smother finish. Using that diluited paint i do a subtle tone next to both lacrimals.

its time to draw what will be the irises, for that and in a diffferent way as i do in a normal bust, i do two circles of Scab Red CC, i give him a coherent and threatening look, but avoiding the perfection of a human look, because, it is an “ugly beast”.

As the color is a bit light i cold draw from now where the pupils are in Black. Them will be elongated as de reptils.

Begin to light the irises, for that i take Golden Yellow CC direct and i outline the pupil first, then i higlight the irises in their inferior part, but, i do it doint little lines and dots to achive the efect of the “draws” on the eyes.

Then i do a mix of the two colors used (Scab Red and Golden Yellow). I apply that mix between the other two colours to smooth the transition, but again dong lines and dots to not achieve a perfect gradation, i’m searching a natural finish.
Done that i begin to light the yellow with White LF more or less in a 2/1 range, reinforcing the higlighting progress done until now.
Now it’s time to add a little more white to the previous mix to do the last lights to the irises. I do a little shadow in the upper part of them, that has been a bit lost when i painted the initial red dot. For that i add a little (so so little) amount of Snot Green CC to the mix used to shadow the balls previously.
I redo the pupils doing them as precise as i could. To end the eyes i do the reflection with a little dot of pure white in the upper part of the irises, a little bit descentrated to give more live to the sight. I highlight the inner part of the eyelid because they are big. To do that i mix a little of Deck Brown with the mix used before to paint that part. To end the whole zone, i delimitate it with black because some parts were excessive width and mount on the exterior of the eyelid.
Hope you like that mini step by step and it will be useful sometime for you!