Almost anything that swings freely can be used as a pendulum, but ideally it should be symmetrical and attached to its cord centrally so that it can swing in any direction. Natural materials such as wood, stone, metal or crystal can all work well, but find one that feels right when you pick it up and swing it, or make your own from whatever you feel is appropriate.
Before you begin, you need to establish the pendulum motions that will mean “yes” and “no” for you, as these vary from person to person. Simply hold the pendulum so it can swing freely and ask “show me the direction for “yes” – note whether the pendulum swings back and forth or in circles, and which way, ie: north/south, east/west, clockwise, counterclockwise. Then steady the pendulum and ask to be shown the answer for “no”, noting its movement. Once the directions are known, ask your question and note the response of the pendulum.
You must reestablish the directional swing of the answers before each pendulum reading session, as the indicated movement can change over time and with different people. A pendulum is a useful tool to help you sense the condition of a person”s aura. You can ask specific questions, as with other kinds of dowsing.