i use dark brown powder and a cotton bud, softer ad defines the eye more, rather than look like you are wearing lots of eyeliner, and less likely to smudge (i have bought cheap liners, expensive liners and they all seem to smudge a little by the end of the day. Not lots but enough to make me look tired).
If you use liner, grey/brown, depends on hair/eye colour, you could even get away with a soft other colour.