Low-End (<100 Hz)
Take away everything below 100 Hz using a high-pass filter with a 24 dB/octave slope. This cleans up any problem frequencies like mic stand rumble, air popping, and other low-frequency noises.
On background vocals, you can use a lower slope of 12 dB/octave HPF and place it around 400 to 500 Hz to free up the low end and clean up your mix substantially.
Body (150 – 350 Hz)
Sweep between 150 to 350 Hz to find the body of the female vocal. If the vocal is too boomy or too thick-cut here with a medium bandwidth parametric EQ to thin the vocal. Boost to give the vocal some fullness.
Nasal (800 – 1000 Hz)
Take away a couple of dBs between 800 Hz & 1 kHz to reduce a nasal sound in the vocal.
Intelligibility (2.5 – 3 kHz)
Boost around 2.5 or 3 kHz for female vocals to increase the intelligibility of the vocal. Used a parametric EQ with a medium to wide Bell.
Sibilance (4.5 – 8 kHz)
Take away some of the harshness (S & T sounds) between 4.5 kHz and 8 kHz by using a narrow bandwidth Bell filter.
Air (10> kHz)
Give your vocal some “air” or “space” by boosting from 10 kHz and up using a Shelving EQ with a medium bandwidth of 12dB/octave.