Here's how I do them:
Start off with your basecoat.
Blot in your white. If you can get it perfect, that's great. But if not, that's fine too. We'll fix it later.
Do the same for the other side.
I thought the figure's right eye was a little to low, so I added some more white.
Next, you can take your basecolour and carefully trim around the edges of the white, slowly making it smaller and the shape you want it. It's much easier to 'trim' the white into what you want, rather than trying to do it perfect from the start. This is also why you want to do the eyes before you do any highlighting on the face.
Here's a shot of a different guy, with his eye white's trimmed.
Then you just need to dot in the eyes. Rather than actually going for a dot, I try to do a vertical line through the white. Again, it's okay if you spill into the skin colour at the tops and bottom, you can easily fix that. If you fins that you managed to get a really thin vertical line that now looks like cat eye's, you can bulk it out a bit.
Here's some shots of completed eyes:
And a close up, doesn't look superb, does it?
But when it's not 500% larger than real life....
I hope that helps.