lol no doubt, i got no idea either. like i said a lot of it depends on the ear.
you also gotta work with the producer too, cause a lot of the cats i work with with make the beat "open" so vocals have centre pan, just the way the beat is made so that the best "spot" for vocals is in the middle of the sound spectrum. if that makes sense.
i also compress and EQ the main vocals, but try not to over do it. its gotta be subtle so it wont take away from the vocals themselves, just clear things up. i meant effects like reverb, echos, tremolo etc...
i dont think there is really one way to do this mixing thing lol. but i know there has to be a foundation.