Using this green illuminated toggle switch is a breeze. First, think about what you want to control. If you want to turn an accessory on and off, use the toggle to connect and disconnect the two pins on the bottom. For the LED, if you want it to be always on, supply a voltage between 3 - 12V between the ground and headlamp pin. If you want it to light up only when the switch is connected, provide 3 - 12V on the (+) pin and connect the ground to the ground pin. When it comes to safety, pay attention to the current. Even though it says '20 A' on the side, it's better to use a maximum of 1 - 2A. Also, be careful while wiring as it's a bit different from regular toggle switches because of the LED and 3 - pin design. For maintenance, keep the switch clean and dry. If the protective cover is getting in the way, you can remove it, but remember it can automatically turn the switch off when closed.