Snap a chalk line on the driveway where you want to cut it. Use blue chalk for this step in a chalk line. The chalk line has a built-in container that holds powdered chalk. As you pull the line out of the case, the line becomes covered with the chalk. When you hold the line tight between two points and snap it, the line deposits a layer of chalk and a creates a line to follow.
Put on safety equipment to include safety goggles, hearing protection, dust mask, pants and a long-sleeve shirt. When cut, concrete makes a lot of dust that is dangerous to breathe. The saw also throws off a lot of small pieces of concrete that can be dangerous.
Place a 1-inch-by-6-inch piece of wood next to the line. A 12-foot piece of lumber will work best for this. The wood acts as a straight edge to run the cut off concrete saw against.
Score a line 1/4-inch deep along your chalked lines with the cut-off concrete saw. The straight edge of the 1-by-6 piece of wood will guide the score line to keep it straight. Walk along the wood to keep it from moving as you score the concrete.
Remove the wood and continue to cut the concrete the rest of the way through. Where you are not cutting all the way across the length of the concrete, you will have to cut past the intersection of where the lines meet in a corner. The diamond blade is round, so there will be concrete remaining in a corner unless you cut past the corner about 3 inches.