How do you hook up a hand held tachometer?

To hook up a handheld tachometer, first, locate the engine's spark plug wire or access the output from the ignition system. Attach the tachometer's clip or probe to the wire or use a reflective tape on a rotating part if it's an optical tachometer. Ensure the device is set to the correct measurement mode (e.g., RPM) and power it on. Finally, start the engine to read the RPM from the tachometer display.