''Demons help humans because they feel it makes them more pure. A number of demons wish to not be seen as evil, and thus want to become angels.'' that is not true demons help us because they want us to be our own Gods like Lucifer said to Eve if you eat the fruit you will not die you can choose between evil and good (free will)and you can also be like God.keep that in mind:D
Respect, in my belief, is of most importance when dealing with entities in the spirit world. Respect spirits the same way you respect people. Treat them as you would like to be treated. They are not objects for your amusement.
Leave it up to the will of the spirit. Not all of them want to hang out with you and be in your séance or move things around. I'm sure they probably aren't up for doing your will. Most of the time you will be seen as petty, and at best you will just find jaded trickster spirits who are tired of being beckoned and will mess with you for their own amusement.
I'm not saying there's anything wrong with summoning spirits. But, I prefer to invite them instead, or I might make a request for protection. Protective and healing spirits enjoy helping people, so they will usually come when you need them. Often times you don't even have to ask, they will just be there. These spirits don't usually need an offering. They love what they do.
Don't forget, intention is one of the key elements of magic. Without establishing your intention, your magic will be aimless. It might help to write down your intentions or speak them out loud. If you are in a group of people all trying to contact spirits, then you should make sure you all agree on your intentions. Speak them out loud. Maybe chant them together as part of a spell. Why are you summoning the spirit, anyway? Just because you can? Because you're bored? If that be your intention, speak it. Maybe entertaining spirits will come visit you. They will appreciate your honesty.
Usually, spirits don't move things around or make sounds or talk anything like that. But, you can feel and sense their presence and be influenced by their energies.
I agree that angels can be annoying quite often, though they are kind, they can be mean as well. For demons, as the first post said, not all of them are bad. That is a common misconception. There are bad demons and bad angels (such as demons that kill and angels of death), and good demons and good angels ( like those who help and heal).