If you summon a demon wrong, it will stay attached to you. It won't leave and it will be very hard to get rid of. They also can manipulate your thoughts, cause fear, and drain your energy. Study hard then go summon one. But study for a long time, not just a few weeks. This isn't a game.
Hey look! A lion! Lets poke it with a stick! Oh my god! Why did you eat my face off?! The moral of this story is dont play with something that could skin you alive, use your skin as a purse and your skull as a candy dish while playing ping pong with your eyeballs. Unless its properly subdued.
Why people want to start off summoning anything is beyond me. *shakes head*