You can only cut in straight lines using a circular hand saw. Because of that, you should mark the cut line before you start cutting. Then attach a blade that is proper for the material that you are cutting. Use the guides to set the blade depth a quarter of an inch below the surface of the material. Before turning on the saw, place the saw shoe on the edge of the material and align the blade with the cutting line. Then lift the blade guard enough to keep it away from touching the surface of the material. Then turn on the saw and slightly push it along the line as you cut.