Step 1 Build Batterboards
Build a pair of batterboards for each run of fencing. Start by cutting points into the ends of two 2-foot 2x4s. Nail a 2x4 crosspiece to them about 2 inches from the top. Drive the batterboards into the ground about 18 inches beyond the planned end points of the fence. Tie mason's line to one of the crosspieces, stretch the line to the other crosspiece, and tie the line in place so it's taut.