Most likely, the first time you summon a demon, it WILL try to kill you without hesitation. I've had issues with demons before, one of which my very experienced friend had to help me kill because it got to the point where I couldn't really sleep or eat or live right. They can mess you up badly...
But first of all, I want to point out that you first need a REASON to summon a demon. It will be of no use to you and will most likely not come if there isn't a reason you need it. Second, make sure that reason is good, because you'll be giving up your most valuable item, physical or mental or spiritual, to that demon. In some cases it might be blood the demon wants, in other cases...unfortunately most...it will ask for your soul, if it likes the color. When you come to terms with the demon, it will "bargain" with you and certain things of which I am forlorn to say will be put into effect. If the demon doesn't double cross you first, then it will carry out your requests and after that, it will kill you and take your soul, or take what it wants.
Second...humans like us can only summon demons on full moons, contrary to what most others believe: that you can summon demons any time you want at any place. That is wrong....like I said before, you may only summon demons on full moons, unless you are a high figure or you are very experienced or you aren't human. What I mean by high figure is someone who has been around and doing these things for at least over 40-50 years or more and they are widely known in this area.
Third...once the bargain has been done, there is no way of undoing it. So make see your decision is final. Demons are tricky. I would not be playing around with this sort of thing if I were you.