Other links to all sorts of fursuit supplies etc here: [link]
This is just to show step by step how I normally paint my eyes. The links above supply the acrylic halves you can use for these. the one that I show being painted here is 1.5 in. Though I do have other sizes, just gauge what size you need for your project :3
You will need:
-Acrylic or resin eye halves
-Cup with water for cleaning brush and paper towel
-Acrylic paint (I use metallic paints for extra shine on the eyes)
-Paint pallet that is probably not as messy as mine
-A little patience for drying times
Start off by choosing a size for your project. For most heads I think the 1.5 in works best but for foam heads that are larger maybe the 2 inch.
Pick out the pupil color, and put a decent sized drop of paint on one directly in the middle of one eye half. Don't worry too much about it being perfect, you can always wipe it clean if you mess up.
After the drop is placed take the two matching pieces and press them together, this flattens out the drop you made making it larger and (hopefully) a perfect circle! You will likely need to practice this a few times, just wipe them clean with a damp towel if you aren't happy with the size or shape. If you make it too small just add another drop and squish them together again. Let this dry thoroughly before moving on.
If you haven't yet, pick out the main color for the eye. You will need to pick a highlight color also but for the time being just mix the main color you choose and darken it down with black or a darker version of the shade you have in mind, this adds depth to the eye. Dry brush this color from the pupil to the sides of the eye and keep it a light coat. You will want it partly transparent, watering the paint down helps with that also.
After that's dry here's where your highlight color comes into play, I chose a yellow for mine but you can just use a lighter shade of your eye color, this is just for a slight hint of color. keep this layer very light.
Once that's done look at the eye, decide if you think its ready for the last coat of color of if you want to add some darker accents to it. You don't always need to but I did for this set. Do the same thing you did before for the darker accents use a darker color, and try to keep it more just at the edge of the eye rather than the whole eye. Darker edges basically.
When that is dry put a flat layer of your desired color, make sure there's no light shining though from the back as that means the paint is thin there, just go back and add another later if you need to.
Then you're all set to install them in your mask!