Team - I've been listening to this again. Highly recommend you put on some headphones/earphones and take a listen to the examples James runs through. This will really help our primary mixing goal: vocal clarity.
I really appreciate these basics:
At the 5:10 mark he gives the payoff - a listen to the mix without EQ and then with the above techniques applied to each vocalist (they are all tonally different, so the EQ slightly varies.)
Check out the video and experiment with these techniques next time you produce a rehearsal!