Two-Wire Volt Tester
The first step is to place one lead on the ground reference which can be a neutral side of an outlet, a neutral white wire, or a box screw. Once done, you should place the other lead on the hot wire or on the hot side of an outlet which is the shorter side of the plug. The same time you place the second lead on the wire, you will be able to read the results on the display of the voltage tester. There should be no light if you have successfully disconnected the electric current, otherwise, the voltage light will be activated.
Non-Contact Voltage Tester
Regardless the type of voltage tester you choose and before you proceed with testing, do not forget to read the manufacturer's review.