Firstly, Ground and protect yourself.
Now hold the chain of the pendulum about 3 inches up the chain, between your thumb and forefinger, wrapping any excess chain around other fingers. Make sure the pendulum chain is hanging straight down, not draped over your thumb or finger - let your wrist go loose You can let out more chain if you like, but the longer the chain the slower it will move. Also being further away from the bodies' energy there is also less definition in the pendulum movements, and more influence by passing air currents.
I usually start my pendulum swinging to and fro to save time. If it has to start moving from a completely stationary position it takes longer and uses more energy. Once it is already swinging it can easily move to the right or left by itself.
Think about your question carefully so that a YES or NO answer can be given. Also, don't 'think' the answer you want to hear or this is what you will get. Ask your question and let your mind go blank. If this is hard to do, then think: "Tell me the truth" over and over so you don't make the answer you want come through your pendulum - otherwise it's pointless asking the question. You will find that when you are practiced you won't need to say your question out loud. You will be able to think your question, so it is important that you do not think your answer.
Ask the pendulum to "Show me a YES". If it is slow to move gently start swinging it to and fro to get the energy flowing and ask again "Show me a YES".
My pendulum moves clockwise for YES, anti-clockwise for NO and gives a diagonal swing for maybe/more info needed. Yours may move in different directions and that's OK. What's important is that between you and your body spirit you get a recognizable swing for YES and NO. Keep practicing until this happens.
Between questions I bring it swinging back to the middle position again to save the time of it having to slow down, and also it will then be in a neutral position for the next question.
This is just one in MANY ways that you can use a pendulum. I would be lost without mine. I even named her.