Take several photos of how the original lines are run then remove the old lines and keep them for reference if needed. Putting in the new lines is fairly straight forward and they will fit into plastic body clamps along their route so you will pretty much know where they are supposed to go. Just pay particular attention to how both lines run around the suspension at the rear left wheel and you should be good.

I did full runs of NiCopp from wheel well to the ABS. No unions to mess with!

BTW I tried several (cheaper) flaring tools but this one was the best. SUR&R » HFT50

Just as an update: This past week I had to replace the front left brake caliper because the piston was sticking. Last year I let the car sit for about two weeks with the rusted brake lines before doing the brake line job and I wonder if the system got some moisture in it because it was open to the elements. As a precaution I replaced all four calipers, the rubber brake lines and put on new rotors and pads to complete a full system refresh.