start with Left Rear then Right Rear the Left Front then Right front, start with the brake line furtherest away from the m/cyl recycle brake fluid untill air is bled then change it with new stuff.How do you know air is in there and how did it get in,did you check you wheel cylinders,leaking seals will give a spongy pedal.Also try clamping lines off while braking this will pin point where the air is.