From the article Mixing and Mastering Tips for Your Music,
Record flat with no effects and instead find the right microphone for the singer. In the mix, roll off everything below 100 Hz and above 12,000 Hz. Add 2-4dB at 160Hz for male vocals or 320Hz for female voice for warmth. Notch out the mid-range, 500-800Hz, by a few dB. Sometimes a little sparkle in the 7-8kHz area is good, if there’s no sibilance there. Finally, a little compression after the EQ can smooth the vocals out nicely.
There are also some tips for doubling vocal tracks, and tweaking reverb for vocal settings.