Use a punch to create a starting point for drilling the hole. This dimple in the metal will help keep the bit centered in the beginning stages of drilling.
Secure the proper sized bit in the drill chuck and place it against the dimple punched in the metal. Place a drop or two of cutting oil on the bit and start to drill the hole. Hold the drill as close to straight as possible and use lots of cutting oil. Drill the hole using a drill press if one is available.
Countersink the opening to the hole and remove any metal chips from the hole after the drilling is complete.
Place the tap in the tap handle. Insert the tip of the tap in the hole and apply downward pressure to the handle while starting to turn the tap in a clockwise direction. It is extremely important to hold the tap perpendicular to the hole as a tap that isn't started straight has a greater probability of breaking during the threading operation.
Turn the tap handle about 1/4 turn and back off slightly. Repeat this process until the hole is tapped. Failure to back off the cut frequently will likely result in a broken tap. Applying cutting oil frequently while threading the hole also helps to prevent tap breakage..