Battening an uneven wall for plasterboard
You simply need to establish lines on opposite sides of your wall, then pull lines between those lines to create the plane for the rest of the boards. Use a level where desired to compare the two initial lines to check for twist in your plane.


Find the high point on one side (or top/bottom, depending on your strategy) and set lines on nails at each corner on that side. Do the same for the opposite side.
Check for twist in the overall plane by checking plumb between the top and bottom corners with a bubble level (and straightedge, if needed). 
Install boards to those lines. Fasten the board at the high point and shim out as needed at the other mounting points. 
Work across the plane established by these two boards, moving a perpendicular line to each mounting line as you go. 


For example, if you're installing vertical furring strips, the first two lines would also go vertically, at the same locations as those strips. Then you'd check plumb on those lines. Then you'd set the first two strips. Now you move your lines to horizontal, against the first two strips, setting the rest of the strips to those horizontal lines. The first two strips act as your reference for all the other strips.