find the eq range of the desired midrange 'punch' that fits the mix and eq of the track (that 'presence' area -2-4k ish).. as well as sounding the correct emphasis... boost it to the desired whatever emphasis (it might sound wrong at first), and apply compression to emphsise the punch or use a signal feed and eq it differently as a sidechain and compress the other frequencies to allow the 'punch/presence' band to emphasise... again emphasis the punch area...
in the mix, you want to hear the vocal, but you dont need to hear the detail of the lower mid and upper bass frequencies, there isn't much definition to anything there, and it muddies up the mix, you need the area where the vocals are formed and the fine top end for sparkle, and bottom for intimacy/closeness
multitracking the BV's gives that rich thickness, if not the actual eq/curve/mix - when mixing blend the takes with different eq's, dont just pile on the eq to the full range on them all..., pick out & 'eq-assign' each take - and effect it correspondignly to do what you want it to do -
like reverb the sparkle/top, NOT the bottom and mid, so you get 'up-front' RnB style 'intimacy' at the bottom end for that FAT warmth with totally 'dry', reverbless bass-end, but the BV take/layer assigned to the top's can have a glistening of sparkly thin subtle reverb with a short decay and enhancer etc - hard-compressing just the boosted mid 'precence' eq'd version add's that accent to the BV's, but NOT loads of sibilance or bass bumping... eq-assigning layers to treatments helps overcome this...
also panning with stereo ch0rus - real signal L - chorus Right or the other way round etc - pan them out - also try panning out the tops, and centering the bass, small MS delays to taste, panned, also add's some superb widening and emphasis , just a slight delay but with pan, so... original L, delay right - each hard-panned - that 'shift' , it just accents when the 'punch' of the first vocal attack hits the speakers but keep the bass free of it - don't muddy... get the fat warmth and the sparkle and the punch-... each eq area doesn't suite the others' processing necessarily, and vica-versa -
oh yes... and an autotuner... :-)