Hello Mick,
Start with the rear calipers, only one bleed screw, then move to the n/s front and finally o/s front. As you bleed them using a clear piece of hose, you will see when the new fluid is through. Keep adding fluid to the reservoir ensuring there is always some in there. Don't let it empty. There is also a fine gauze trap at the bottom of the reservoir which might be grubby. If so, remove and clean by rinsing in brake fluid.
Are you doing it by yourself using a self bleeder or are you having an assistant pump the pedal while you work the bleed screws? Also put some clean brake fluid in the bottle that you put the hose into, making sure that the end is submerged. With a self bleeder, certainly in the case of the one that I have, this is not required, but if you don't use one then you will need to put some fluid in the bottle to start.
Ron..