I have interacted with multiple spirit entities, mostly human, but a few non-human. Humans from what I have seen as spirits can appear to you as transparent, fully physical, invisible with a heat wave effect, complete black entities, and as white mist like looking entities. Angels smell wonderful when they are around. Archangel Michael smells like roses or Chanel Number 5, and Archangel Raphael is a big hugger and will show up in dreams when called upon. Knowing his presence is being hugged by someone in your dream! The only non human entity that I have ever seen physically were insects that resided in that dimensional plane, they were alien looking indeed. But just like in our world there are good and bad people. No difference in the spirit world. Many spirits want to manipulate you to gain control or feed off you. But then there are those that want to save their soul and to progress in life who would be willing to help you if you help the denizens of there dimension which would in turn help their soul for those that cant cross over into the light, but want to. Elementals are very active in the spirit world those that are bad and those that are good. I have met entities known as The Builders which are some kind of entity but their presence feels cold and not great. Banshees will sometimes try to interfere with my sessions when I guide spirits into the light but they are easily able to ignore as you focus on your intentions. Spectres are like spies for Wraiths I think which is some kind of sick twisted form of being bound to Wraiths as they could have been murdered or done wrong by the Wraith in their previous life and couldnt let go. Giants reside in the spirit world as well, never seen one but the spirits say that they are there and they do get attacked by them. Another entity is known as an Elder which is what spirits call them which I think are the Lizard People but not for sure. Then their are demons, they do exists but I do not pay no mind to them as I focus on the Light as best I can having guidance in God and his Angels to watch over me.
Another thing when it comes to good or bad spirits is what you feel too. For good spirits I will feel a light tingle feeling on my body or crown when something good is close. But I will get a sharp pain either in the back of my neck or kidney when a darker entity was close or trying to attack me. I try to focus on working with God, Angels, Guides and Ancestors which have naturally been able to help me in guiding me in my studies. Good tool to use for those that want to interact with spirits, use Ghost Hunting Tool. The reason I pick that one is because I've seen human spirit entities physically use it to be able to communicate with me. Good luck on your adventures.