My method for eyes depends on how well defined the eyesocket is in the sculpt, but as an example for the Sascha DuBois I did earlier thie year here's how It went.
Thin down either chocolate Brown or Leather Brown from Vallejo Model Colour, use this to 'set' the eye socket. Allow to dry.
Support your two hands together holding the miniature.
Now with your primary Hand, paint the eye Nearest to that Hand, using Vallejo Model Colour Ivory. (Ivory is less of a startling colour for eyes than plain white.)
Turn The Model Upside Down and paint in the other eye.
Now remember that in real life the iris/pupil looks to take up 1/3 of the available area of the eye, so when painting that in allow for that and the eyelid cover.
Normally the eyelid covers part of both the top and bottom of the iris, and if you just "dot" in you end up with the "thousand yards stare" effect.
Also try to get the iris placement even avoiding the "boss eyed look".