I work with spirits and Exorcisms. It's something I don't suggest for everyone to be honest, you get your good, your decent, your neutral spirit and then the bad ones.
Funnest incident I had was the fact the spirit that was messing with us for a bit. Oddly enough with the mention of Halloween, or alike holidays like Samhain, it'd toss something to the floor etc.
I was in the room by myself, at the end of the bed. A pillow hit my head. A pillow?! really. Though I wasn't complaining.
Also I've read that if you've ran into a spirit that's holding you down at night, putting pressure on your, etc. Please do go to someone that can rid of spirits; even your church can. =/
If you don't know what your doing don't attempt to rid of em, I use a smudgestick of sage myself, and or holywater if its present. One thing to remember is to stay focuse minded and basically believe you are stronger than them. If you give them the strength to beat you well... Aye.
I've seen spirits too many times to really say. One time I stepped out of my bedroom and looked down to the hallway to the basement and a shadowy figure of a man was standing there, but as tall as the doorway its self. I could see his clothing wasn't from this time. He had long raven black hair down his shoulders, a very angular pale face. Some sort of dark colored shoulder pad/armor and a long flowing came that wrapped around the shoulders some what and hung down. He basically wore nothing but black. And then he was gone. Apparently the younger sibling of the house hold had seen him standing over his bed before as well. I can't really think of anything at the moment.