After I've drained all the water out of the drain plugs and put them back in I pull the thermostat housing and pour the antifreeze directly in the motor till it fills to the top of the thermostat hole. I also pour it directly down the hoses into the exhaust manifolds. That way I know there's not any water in the system to dilute the antifreeze. As far as the rest of the raw water lines I just make sure they're drained.