Vocal Mix Cutting.

I came across this great trick on reddit. When you're struggling to get a vocal sitting right in the mix, you can do an all round cut of everything but vocals at around 2.5khz of only a few decibels and it will not effect the tone of the instruments but will make the voice sit a lot more comfortably in the mix.
Another variation of this is to have a multi band compresser side chained to the vocals so that when the vocals come in, the compresser kicks in and reduces the high mids, meaning the vocals can "take front".