Well, assuming the super nature is true and what u see is, what u think it is, it is hard to tell.
From a scientific point of view, soul/ghost/gods/reincarnation, is the energy use within the nerve system. Like all house hold appliance, the human nerve system, run on electricity. However, energy can neither be created nor destroy, but can only transform from one form to another. the energy our nerve system use come from external source, and enter our body around 3~4 months pregnancy and is release back into nature, after our death, until it enter a new host what we refer to as soul/ghost/gods/reincarnation, is believe to be mythology that develop from that transferring, most psychic would also say when they contact the dead, they sense their energy. However, scientifically there are not yet evidence that energy retain conscious of the person it was once a part of, neither are there evidence that energy contribute to making our conscious exist. So we can't tell whether a ghost is dangerous or not, from a scientific point of view.
Assuming ur idea is accurate, ghost itself can be benefit or disadvantage, it is one person and also many person, so it could be a love one from past or current life, it might be somebody that is going to reincarnate as ur child one day, it might be somebody who have positive or negative relationship with u in past or current life, others, are just good or bad people. We can't really tell.
To prevent evil spirits, there are numerous pagan mythology that is still use by modern pagan priests, priest of each religion have strength and weakness in dealing with supernature, in general, Christian priests are the weakest, but they too have strength that surpass other religion.
The Chinese pagan faith believe, possession ghost enter ur body from ur ass, so if u clutch it together it can stop the ghost from entering (or u can always stick a piece of tissue there) japanese pagans believe, salt can help drive away unwanted spirits.
In my experience, Buddhist priests are usually the most powerful, in dealing with super nature, so, if u truly believe in what u see, I would recommend u talk to a Buddhist high priest and see what they got to say. I won't recommand Christian priest as 1st choice, because in most arena of dealing with supernature, christian priest either have no power , little power or is totally off track, although in some arena, they can still be powerful,