I started out with it swinging toward/away from me for yes, and perpendicular (from left to right) for no. As I got more into it, and started using charts, I programmed it to swing about 45 degrees to the left for no and 45 deg right for yes. But you can program it any way you like. James' yes and no are opposite to mine, for instance.
You can say "show me yes" and see where it swings, and the same for "show me no". Or, you can say swing this way for yes and that way for no, and make it comfortable and clear for you. Then test it with some simple, obvious questions/statements, like "I am a cat" or "Today is Tuesday". Get the simple, obvious things practiced before you get into more complex questions.
Karla's really good with pendulums, too, though at this point I don't think she uses them. It's possible and probably likely that eventually you wouldn't need it.
Another thing I do for simple yes/no questions is to stand and let my body lean forward for yes and backward for no. It's just a slight movement but perceptible, and is handy when you're out in public and want to check in on something.