I was always taught that to unload meant to not have any stick input for the elevators, which would mean that regardless of what heading you was pointed at up - down - diagonally, you would still be at the 1G+
like if I was lining up for a shot, I would unload my plane before firing
zoom climbs / zoom dives I was taught was 0 G for maximum effect
you professionals correct me if I am incorrect please