The human voice is probably the most challenging instrument to record.
Every singer has a unique voice.
Some sing loud and some have better microphone technique than others and some sing quietly and more breathy. It is hard to apply any of the same rules from one singer to the next. There are some basic settings that will help get you started, but from there you have to tailor the signal path and processing for each individually. Three things that are important to pick up on when recording vocals are mike technique , sibilance , and tone . This is a good time to size up your singer too.