This is my view on how to get rid of unwanted spirits based on my knowledge and experience with ghosts.
Ghosts are people without bodies and as such they retain the same personality they had when alive. Most ghosts are not dangerous and some are very helpful.
However if you find yourself with a malevolent spirit I would never suggest to have what some people call exorcism done on the house. Actual exorcisms are done on people and that is another topic altogether, but many modern ghost hunters use this word for the religious ritual of saying I rebuke you in the name of Jesus or some other Deity. Waving crosses or other religious symbols around the room chanting words like I exorcise you etc.
This may seem to work for a while but usually ends with the ghost returning and makes them angry.
The best way to get rid of unwanted spirits is to just talk to them like you would if they were still alive. Rebuking a ghost in the name of some Deity will not work any more then rebuking a robber with a gun robbing a bank. This only angers the humans and ghosts.
Spirits are attracted to certain people at times because of their personalities. You know like attracts like. A lot of times a malevolent spirit is attracted to someone due to the way they act and think. Drug abuse and alcoholism and depression can at times attract malevolent spirits and the only way to completely rid oneself of these spirits is to get rid of the attitudes addiction etc that is causing this. That is a work with inside oneself.
Now one thing I do is to cleanse the negative energy within the walls of a house thus making It undesirable for the malevolent spirit, but the real work comes from inside the person attracting the spirit.
A home full of fighting, yelling screaming will not attract benevolent spirits but negatives ones.