Auto body repair & detailing: body lines, straight body, masking tape

Question
In am nearing completion of my first restoration project. I am however having problems getting straight body lines on the rear 1/4 (horizontal crease in panels).

Do you have any tricks of the trade to make this job easier or is it merely persistance and training the eyes?

Answer
  hi steve,
     i don't know what kind of car you have or what paticular body lines you have ,but i sometimes run a piece of masking tape along the line and sand the filler to the edge of the tape.then run tape on the other side and sand to it. this will get you pretty close the rest is just eyeing it. you could also spray a light coat of primer on the filler before taping ,this will help you see how straight the line is after sanding. thanks for writing.

                                          dave........