Marking Out

The plans clearly show those parallel gridlines and once you have drawn them across the sheet, they are in the right place for all the other pieces too.

Rule off all the straight panel lines with a nice heavy (but not too thick) line, so you won't mistake them for the grid lines when you come to cut them later.
 

I have been known to use a fine red felt pen for the gridlines to get around that confusion, but you have to be sure you sand them off later, red stripy dinghy interiors went out in the 60's.