Meditation
A good way to start off communicating with Demons is to start meditating. Shutting your mind down from this noisy world will allow you to hear things of other worlds. Go to your private room light some incense and a candle. Relax, close your eyes, and tune into your breathing. Clear your thoughts and go into yourself. At first clearing your thoughts will be hard however, just keep throwing them away and they will know to stay away during this time. Meditate for at least a hour everyday for things to work. Skipping a day will just make the next time harder. After awhile you can ask if a Demon will come to you. Wait, with regular meditating your mind will open and you may begin to feel a Demon's energy around you. You can ask if they will show you an image and you may see them in your minds eye (third eye) located in your forehead; this is what you are opening up. You can also talk to the Demon and you may start hearing their voice talk to you in your head. Everyone is different, and these areas open up at different times.