This is a three part video tutorial. The author uses a bandsaw to hog out some of the material in the rough cutting stage. This is handy but not necessary. Use a sharp chisel from both sides to prevent chipping on the underside of the cut. Some people will use a sharp drill bit to remove the waste that the bandsaw removes in this video.
If you work only with hand tools, start like the author does, by leaving a small amount of material behind when making the rough cutout. Then pare to the line with a sharp chisel. Again, work from both sides of the material to check for square work and prevent chip out.
If anyone would like to practice this work at home, we can arrange to loan you a bag with the tools needed and some scraps of practice lumber.